0, gentle sleep, Nature's soft nurse.
- Shakespeare (1564-1616).

Embrooded was he, as it were a mede,
All full of freshe floures white and rede;
Singing he was, or floyting all the day;
He was as freshe as is the moneth of May.
    - Description of the Squire in Geoffrey Chaucer (1340-1400).
 

 (A) ANATOMY.

    The abdominal brain or ganglion coeliacum has experienced multiple names during the past three centuries.
    Synonyms. - Celiac ganglion (ganglion coeliacum); solar plexus (plexus solaris, Todd and Bowman, 1847); semilunar ganglion (ganglion semilunare); the great abdominal ganglion (ganglion abdominale maximum); abdominal brain (cerebrum abdominale, Wrisberg, 1780 [1739-1808]); the nervous center of Willis (centrum nervosum Willisii, 1622-1675); epigastric nervous center (centrum nervosum epigastricum); splanchnic ganglion (ganglion splanchnicum); vascular abdominal brain (cerebrum abdominale vasculare); epigastric plexus (plexus epigastricus); celiac plexus (plexus cceliacum).
    Some authors have viewed the abdominal brain or celiac ganglion as composed of two parts, right and left, bilateral and paired.  I shall consider it as practically one sympathetic ganglion or plexus anatomically and physiologically, and term it the abdominal brain - the celiac ganglion, a coalesced, vascular, visceral brain, unpaired, existing at the origin of the celiac, superior mesenteric, and renal arteries (major visceral arteries).
    The arrangement of the abdominal brain consists of: (a) afferent or centripetal nerves (entering or contributing nerves from the cerebrum, spinal cord, or sympathetic); (b) efferent or centrifugal nerves (distributing or visceral).  The afferent nerves enter chiefly on the proximal and lateral borders, while the efferent nerves radiate from all regions of the abdominal brain - hence solar plexus.  There is no relation between the number and dimension of afferent and efferent nerves of the abdominal brain.
    (a)  Afferent nerves.  The afferent or contributing nerves composing the abdominal brain are: (sympathetic), (1) plexus aorticus thoracicus (unpaired); (2) nervus splanchnicus (paired), constituting the most essential portion of the abdominal brain; (3) branches from the two proximal lumbar ganglia (paired): (cerebrospinal) I, nervus vagus (paired), especially the right; 11, nervus phrenicus (paired), especially the right.  The abdominal brain consists of the coalesced termination of the above (1, 2, 3, I, II) five nerve apparatus.  The abdominal brain is the major assembling center of the abdominal sympathetic.
    (b)  The efferent nerves.  The efferent, visceral, or distributing nerves of the abdominal brain of various caliber radiate in a plexiform arterial sheath to every abdominal viscus, viz., to the tractus intestinalis and its appendages: plexus hepaticus, lienalis, gastricus, mesentericus superior, mesentericus inferior, heemorrhoidalis; to the tractus urinarius: plexus suprarenalis, renalis, ureteris, vesicalis, urethralis; to the tractus genitalis: plexus ovaricus, hypogastricus (pelvic brain), plexus uterinus pudendalis vaginalis; to the tractus vascularis and tractus lymphaticus.  The abdominal brain emits plexiform nerves and ganglia fixed in connective tissue sheaths which intimately encase the vascular tubes.  The nerves emitted from the abdominal brain are gray or white in color, limited in diameter, plexiform in arrangement, resist tension on account of the thick fibrous neurilemma, and ganglia are liable to occur at their points of crossing or anastomosis.  The radiating, efferent nerves of the abdominal brain accompany the arteries arranged in a plexiform sheath or network.  They do not accompany the veins - the trunk of the vena portae being the only exception.
    I.  Position: Holotopy (relation to general body).
    The abdominal brain is located at the proximal end of the abdominal cavity immediately distal to the diaphragm.  It is situated medially, extraperitoneally, and is practically bilaterally symmetrical.
    II.  Skeletopy (relation to osseous skeleton).
The abdominal brain corresponds to the level of the first lumbar vertebra, on its ventral surface.
    III.  Syntopy (relation to adjacent organs).
    The syntopic relations of the abdominal brain are intimate and profound connections with vascular and visceral organs.  It surrounds the roots of the celiac, superior mesenteric, and renal arteries like a collar or fenestrated sheath.  It is located extraperitoneally, on the ventral surface of the aorta and crura of the diaphragm.  It is situated immediately distal to the hiatus aorticus of the diaphragm.  It lies between the diaphragmatic and renal arteries.  Right and left it projects against the capsules of the adrenals.  It is located between the proximal renal poles.  It lies partly dorsal to the corpus pancreaticus and stomach.  Its right half lies between the right crus of the diaphragm and the vena cava.  Practically the abdominal brain is lodged in the space bounded bilaterally by the adrenals and proximal renal poles; proximally by a line drawn transversely from the proximal point of one adrenal to that of the other; distally by the renal arteries.  The situation of the abdominal brain is included within the space of origin of the celiac and renal arteries - some two inches.
    IV.  Idiotopy (relation of component segments).
    The component parts of the abdominal brain are from proximal to distal end in order, viz.: (a) The projecting ganglia of the origin of the diaphragmatic nerves located on the proximal border - conical elevations or bulb of the brain itself; (b) the semilunar ganglia, the essential material in form and dimension of the abdominal brain, constituting its major central segment; (c) the renal ganglia, located generally at the origin of the renal arteries, are practically constant, however varying in location, form, and dimension.  The segments proximodistally are compactly and solidly united by ganglionic masses, flattened commissures, and nerve cords along the lateral borders of the aorta.  The segments laterally, i.e., the right half and left half, are united transversely around the roots of the celiac, superior mesenteric, and renal arteries by ganglionic arches, flattened commissures, and nerve cords extending transversely from the right to left half of the brain.
    Dimensions. - The abdominal brain or celiac ganglion is the largest and richest ganglion of the sympathetic nerve.  Hence from a preponderating aggregation of nerve cells it becomes the ruling potentate of the viscera.  The left half is more compact, greater in dorsoventral diameter, thicker, less fenestrated, and possesses more definite regular borders than the right; however, the right half is greater in surface area.  Its diameters are: (a) transverse about 11/2 inches; (b) proximodistal 1/4 inches; (c) dorsoventral about 1/6 inch.  The dimensions of the abdominal brain practically correspond with the space bounded bilaterally by the two adrenals and the two proximal renal poles; distally by the two renal arteries; proximally by the diaphragmatic arteries, or a line drawn transversely from the proximal end of one adrenal to that of the other.  Its surface dimensions vary extremely on account of the indefinite coalescence, interpolation, distribution, dislocation of ganglion or by transportation along visceral vessels.
    The Form. - The form of the abdominal brain is variable; however, in general it is quadrilateral.  It may present a half-moon or horseshoe shape, or a ring surrounding the celiac axis and superior mesenteric artery.  It may also be represented by a single broad fenestrated ganglionated plate which covers the ventral surface of the aorta adjacent to the celiac axis, and occupies the space between the adrenals and proximal renal poles.  The left half may resemble a bean, a retort in compact form, while the right half is more quadrilateral, flattened (from compression of the vena cava), and irregular in contour.  The form has changed by development from coalescence, interpolation, isolation, and transportation of ganglia along visceral vessels, the vertebral column and ribs.
    The Borders. - The borders of the abdominal brain (margo cerebri abdominalis) are four, viz.: proximal, distal, and two lateral. (a) The proximal border presents three factors of interest.  The first is the concave horseshoe-like depression made in it by the celiac axis and the surrounding of the vessel like a collar by nerve cords and ganglia in a connective tissue sheath.  The other two factors are the cone-like projections of a portion of the brain which emits bilaterally the nervus (plexus) diaphragmaticus.  The proximal border receives the continuation of the nerves of plexus aorticus thoracalis as well as the termination of the right vagus (cranial), and also communication may occur with the right nervus phrenicus.  The proximal border is generally blunt and rounded.  Practically the plexus Lyastricus is emitted from its proximal border. (b) The lateral border (left) presents quite an uneven line, with irregular projections for efferent nerves, chiefly destined to the adrenals and kidneys, and for afferent nerves, especially the major splanchnic.  The main projections along its border are those produced by the ganglion splanchnicum and ganglia renalia. (c) (right).  The lateral border is generally an irregular line caused by the irregular size and location of the ganglion splanchnicum and ganglion adrenalis.  The lateral borders receive (afferent) nerves (splanchnic major) and emit (efferent) nerves (plexus adrenalis and plexus renalis). (d)  The distal border is bounded by the arteria renalia - practically an even line. it emits or distributes efferent nerves of various caliber to the abdominal visceral tracts.
    Fenestrae. - The compact left half of the abdominal brain may be limitedly perforated, while the widely meshed right half is considerably fenestrated with larger and smaller, irregular-shaped apertures adding unevenness to the surface.  The fenestrae possess sloping, smooth, irregular contoured edges and are occupied with connective tissue, blood and lymph vessels, glands, and areolar tissue.  The chief central fenestrae are produced by the celiac axis and superior mesenteric artery.  The left half of the brain generally has one major fenestra due to a blood-vessel springing from the aorta.  The right half of the brain possesses some three definite apertures, large ones.  In general the right half possesses two kinds of fenestrae, viz.: (smaller) those in the more solid median division of the brain, and (larger) those in the lateral, more widely meshed portion.  The splanchnic ganglia, located at the termination of the splanchnic nerves, are situated in the middle of the celiac plexus and represent the major ganglionic masses.
    The Surfaces. -  The surfaces of the abdominal brain (facies cerebri abdominis) consist of two, viz.: (a) the ventral, (b) the dorsal.  The ventral surface is uneven, from coalescence of smaller and larger ganglia, irregular coalescence, compression of adjacent viscera (as the inferior vena cava), or dislocation of ganglia by transportation along vessels.  The ventral surface is convex from the dorsal compression of the aorta and crura diaphragmatica.  The ventral surface receives (afferent) and emits (efferent) nerves; also may be observed nerve loops which originate and insert themselves on the ventral surface.  From the ventral surface pass the nerves to the adrenal, pancreas, and plexus renalis - in fact, the nerve plexuses accompanying the branches of the celiac axis and many of the plexus rnesentericus superior from the ventral surface.  The surface is solidly bound by connective tissue to adjacent structures.  The ventral surface of the left half of the abdominal brain is concave from the contact pressure of the cylindrical aorta and crura diaphragmatica.
    The fenestrae or perforations of the dorsal surface correspond with those of the ventral.  Strong, fine white strands of connective tissue, blood, nerves, and lymph vessels bind the dorsal surface of tne abdominal brain solidly to the crura diaphragmatica, but especially strong to the aortic.  Nerves originate and depart from the dorsal surface.  From the dorsal surface nerves depart to the aorta and diaphragm and the splanchnicus major, bilaterally, arrives on the dorsal surface.
    Ganglia. - There are usually six constant ganglia in the abdominal brain, viz.: (a) Ganglia diaphragmatic (paired). (b) ganglia splanchnica (paired); (c) ganglia renalia (paired).  They are solidly and compactly united into one anatomic and physiologic nerve center - a brain.  In general the ganglia do not agree in form or dimension bilaterally.  Practically the ganglia agree in position bilaterally.  However, the left semilunar ganglion is nearer the median line than the right, and the left mainly lies on the aorta, while the right chiefly rests on the crus of the diaphragm.  The ganglia may rest in an even transverse plane, or lie in superimposed layers in a dorsoventral plane.  The ganglia constituting the abdominal brain are as irregular and variable as the plexus in which they are located.  The ganglia consist of large, swollen cords, or ganglionic arches or circles arranged in a network.  The dimension, form, and number of the ganglia may vary from coalescence, isolation, interpolation, or transportation of ganglia along vessels, bones, and muscles.  The coalescence of the ganglia may proceed to such an extent - that the abdominal brain will present the appearance of several nodes, or the two semilunar ganglia may coalesce and lie between the celiac and superior mesenteric arteries.
    The ganglia may coalesce proximally and distally in the form of a ganglionic ring surrounding the origin of the celiac and mesenteric arteries.  The ganglia of the abdominal brain may be flat or elevated, single or multiple, united by gangliated commissures or flattened nerve strands.  The nervus splanchnicus major, the essential segment, terminates bilaterally in the abdominal brain in a large semilunar or quadrilateral-shaped nodule-ganglion splanchnicum (paired).  The splanchnic ganglia may assume the shape of the letter C. I have seen two splanchnic ganglia on each side of almost equal dimensions formed by the splanchnic major and minor nerves.
    1. The left semilunar ganglion has a more definite border, is nearer to the median line, greater in dorsoventral diameter, more compact, yet smaller and less fenestrated than the right.  It lies transversely on the side of the aorta between the renal and diaphragmatic arteries.  Its average diameters are: proximodistal, 1/2 inch; transverse, 1 inch; dorsoventral, 1/6 inch.  Its thickest border is the left, its thinnest is the right.  Its ventral surface is uneven, convex; the dorsal, concave.  It is flask or quadrilateral in form.  The right proximal angle is elongated into a horn-like process to join its opposite fellow.  Afferent nerves arrive and efferent nerves depart from all surfaces and borders except part of the left.  Proximally, it is connected with the diaphragmatic ganglion - externally with the splanchnic nerve, medially with the opposite fellow (right half of brain).
    2.  The right semilunar ganglion is more flattened, greater in surface area, more extensively fenestrated, and less in dorsoventral diameter than the left.  It lies between the vena cava (ventral) and right crus of the diaphragm (dorsal); and between the renal and diaphragmatic arteries.  Afferent nerves arrive and efferent nerves depart from its surfaces and borders.  The left, proximal, angle is prolonged into a horn-like process to join its opposite fellow.  Proximally it is connected with the diaphragmatic ganglion, distally with the renal ganglion; externally with the splanchnic nerve; and medially with the opposite fellow (left half of the brain).
    Ganglion of the Phrenic Artery (Ganglion Arteria, Phrenicae). - In this brief note I wish to present a sympathetic ganglion (bilateral) which I have not found described in literature.
This ganglion consists of a constant pyramidal, or cone-shaped projection on the proximal border of the abdominal brain in the course of the phrenic artery.
    In Fig. I on the right side it is located by a hook at the figure 2 in the abdominal brain.  On the left side it is located between the splenic and phrenic artery.
    The phrenic ganglion projects bulb-like from the proximal border of the cerebrum abdominale similar to that of the olfactory nerve from the cranial cerebrum.  It is a part and parcel of it.  By a general observation in dissecting the sympathetic nerve (nervus vasomotorius) it will be evident that sympathetic ganglia are located at the origin of the vessels from the aorta, as at the foot of the celiac axis (ganglion semilunare) at the origin of the renal artery (ganglion renale) at the origin of the arteria mesenterica inferior (ganglion mesentericum inferius) at the origin of the two common iliacs from the aorta (the interiliac nerve disc), and so forth.  Hence it is in accordance with this rule that the ganglion arterix phrenicae is found in the course of the phrenic artery (bilateral).  If the phrenic artery has an anomalous origin and course the phrenic ganglion tends to follow its origin and course, and it was this anatomic relation that called my attention to this heretofore undescribed constant ganglion.  I do not refer to the diaphragmatic ganglion (ganglion diaphragmaticum) located on the diaphragm on the right side (only) about two inches from the abdominal brain.  The abdominal brain consists practically of three ganglia (bilateral).  They are: 1. Ganglion semilunare (bilateral), located on the middle part of the lateral border of the abdominal brain at the termination of the major splanchnic nerve (Sp. in figures).  This ganglion is related to the origin of the celiac artery.  2. Ganglion renale (bilateral), located at the distal lateral border of the abdominal brain, and belongs to the origin of the arteria renalis.  3. Ganglion arterioe phrenicae (bilateral), located at the proximal border of the abdominal brain in the course of the phrenic artery.
    In certain subjects the ganglion of the phrenic artery is located exactly at the origin of the phrenic artery from the aorta.  However, the origin of the phrenic artery varies considerably, and this alters to some extent the relations of the phrenic ganglion from physical facts.
    The phrenic ganglia are constant structures, constantly located in relation to the course of the phrenic arteries so far as I can determine by dissection.  The importance of the abdominal brain, with its ganglia, will sooner or later be realized by the general profession.
    The diaphragmatic ganglia are practically bilaterally symmetrical in location, form, and dimension.  They project as pyramids or cones from the proximal border of the semilunar ganglia, at the origin of the diaphragmatic arteries, giving origin in the diaphragmatic nerve.  They project from the abdominal brain as the olfactory projects from the cranial brain - being a part of it.  The diaphragmatic nerve possesses a small ganglion some 2 1/2 inches from its origin, and it anastomoses with the right phrenic.
    5 and 6. The primary renal ganglia are practically bilaterally symmetrical in form, location, and dimension.  Their location is generally at the origin of the renal arteries.
    I. The ganglia of uncertain dimension, location, and form associated with the abdominal brain are: (a) The nervus splanchnicus minor terminates bilaterally more distalward generally on the renal arteries; (b) the ganglion suprarenale supernum, which I have occasionally found chiefly on the right suprarenal nerves.  The color of the abdominal brain is grayish-red; the consistence is moderately dense, due to the presence of abundant connective tissue; the composition consists of an aggregation of nerve ganglia, ensconced in dense connective tissue, varying in dimension, number, and form.  Each ganglion is composed of oval-shaped nerve cells of various form and dimension.
    Relations. - The relations of the abdominal brain well encased in fibrous and connective tissue consist in intimate connection with the abdominal aorta at the origin of the celiac axis, superior mesenteric and renal arteries.  It has also intimate but less solid connections with the vena cava and renal veins.  It is a vascular brain of the abdomen.  The abdominal brain lies in the square formed by the proximal renal poles with adrenals and the renal arteries.  It is in relation to the dorsal surface of the body of the pancreas, peritoneum, and stomach.  The abdominal brain in general occupies the space including the origin of the major visceral arteries, viz.: (a) arteria coeliaca; (b) arteria mesenterica superior; (c) arteria renalis - three mighty visceral arteries originating from the aorta within the space of an inch and a half.  Hence practically the term abdominal brain should include the aggregated or coalesced ganglia located at the origin of the major visceral vessels.  With development of viscera and elongation of visceral arteries, the ganglia become isolated from the original abdominal brain and transported along the vessels toward the viscera.
    The two best examples are the renal and aortic arteries with their numerous transported large ganglia - ganglia renalia and ganglia aortica.  Development has sometimes separated the cord and ganglion of the nervus splanchnicus minor from the abdominal brain by placing it more distalward and lateralward toward the region of the origin of the arteria renalis, thus altering the form and contour of the abdominal brain.  The nerve plexuses and ganglia of the abdominal brain, firmly bound in sheaths by strong white connective and elastic tissue, encase the visceral vessels and accompany them to the viscera.  The abdominal brain is solidly and compactly anastomosed, connected by nerves of various caliber with all the abdominal viscera, viz., tractus intestinalis, urinarius, genitalis, vascularis, lymphaticus.  It is evident from its location at the origin of the celiac axis and superior mesenteric arteries that the abdominal brain in its origin was a primitive brain for the tractus vascularis.  With development of viscera and elongation of visceral arteries, dislocation, multiplication, distribution, coalescence or transportation, of ganglia, other viscera have acquired local ganglionic rulers, e.g., the pelvic brain - ganglion cervicale.  However, present conditions allow the origin of the abdominal brain to remain at the exit of the major visceral vessel.  It should be denominated a vascular brain.
From the abdominal brain radiate plexuses of various caliber, chiefly in vessels, to all the abdominal viscera, viz., tractus intestinalis, genitalis, urinarius, vascularis, and lymphaticus.  The abdominal brain emits more nerves than it receives, and hence is a creating, producing center, a source for new and increased nerves.  Nerve reception occurs chiefly at the proximal (plexus aorticus thoracalis, vagi) and lateral borders (splanchnics, major, medius, minor).  Nerve emission occurs mainly at the distal (plexus aorticus abdominalis) and lateral borders (plexus renalis, adrenalis).  From the dorsal and ventral surface, from the bilateral proximal and distal borders of the abdominal brain, nerves arrive and depart.  Bilaterally radiate the renal and adrenal nerves, and arrive the splanchnicus; proximally radiate a few to the aorta, and arrives the plexus aorticus thoracalis and vagi; dorsally many nerves pass to the aorta and diaphragm, and arrive the branches from the splanchnics; ventrally a number of nerves radiate to the adrenals and pancreas; distally are emitted nerve plexuses of vast importance on visceral arteries of corresponding names, viz.:
    I.  Tractus intestinalis: (1) Plexus coeliacus, emitting (a) plexus gastriticus accompanying the arteria gastrica; (b) plexus hepaticus accompanying the arteria hepatica; (c) plexus lienalis accompanying the arteria lienalis. (2) Plexus mesentericus superior accompanying the arteria mesenterica superior (to the enteron - except the duodenum, and colon, except the caecum, right colon and right half of transverse colon). (3) Plexus mesentericus inferior accompanying the arteria mesenterica inferior (to the left half of the transverse colon, left colon, sigmoid flexure, and rectum).
    II.  Tractus urinarius:  (1) Plexus adrenalis accompanying the arteria adrenalis. (2) Plexus renalis accompanying the arteria renalis. (3) Plexus ureteris accompanying: (a) rami arteriee renales; (b) arteria ovarica; (c) arteria ureteris media (from common iliac); (d) arteria uterina. (4) Plexus haemorrhoidalis accompanying the arteria haemorrhoidalia.  (5) Plexus hypogastricus accompanying the arteria hypogastrica. (6) Pelvic brain (ganglion cervicale) emits nerves which pass directly to the ureter without accompanying blood-vessels as well as the plexus vesicalis. (7) Plexus vesicalis accompanying the arteria vesicalis superior, media, and inferior (hemorrhoidal). (8) Plexus urethralis (a continuation of the plexus vesicalis) accompanying arteria pudenda.
    III. Tractus genitalis:  (1) Plexus aorticus accompanying the arteria aortica abdominis. (2) Plexus hypogastricus (a continuation of the plexus aorticus) accompanying the arteria iliaca communis and arteria hypogastrica. (3) Plexus ovaricus accompanying the arteria ovarica. (4) Plexus arteriae uterinae, accompanying the arteria uterina. (5) Cerebrum pelvicum (pelvic brain), which emits the plexus uterinus without accompanying vessels as well as the plexus vaginalis.  The sympathetic nerve cords and ganglia accompanying vessels (blood, particularly arteries and lymph) arranged as a network in a connective tissue sheath which encases the vessel.

(B) PHYSIOLOGY OF THE ABDOMINAL BRAIN.

    In mammals there exist two brains of almost equal importance to the individual and race.  One is the cranial brain, the instrument of volitions of mental progress and physical protection.  The other is the abdominal brain, the instrument of vascular and visceral function.  It is the automatic, vegetative, the subconscious brain of physical existence.  In the cranial brain resides the consciousness of right and wrong.  Here is the seat of all progress, mental and moral, and in it lies the instinct to protect life and the fear of death.  However, in the abdomen there exists a brain of wonderful power maintaining eternal, restless vigilance over its viscera.  It presides over organic life.  It dominates the rhythmical function of viscera.  It is an automatic nerve center, a physiologic and an anatomic brain.  Being located at the origin of the celiac, superior mesenteric. and renal arteries - the major abdominal visceral arteries - it is a primary vascular brain of the abdomen and a secondary brain for visceral rhythm.  The abdominal brain presides as the central potentate, over the physiology of the abdominal viscera.  The common functions of these viscera are rhythm, secretion, and absorption, and to preside over this triple office is the chief duty of the abdominal brain.  To the common functions of the abdominal viscera must be added tb especial functions of the tractus genitalis - ovulation, menstruation, gestation; however, many of the functions of the visceral tract are delegated to the subordinate local ruler - the pelvic brain.  The abdominal brain is a receiver, a reorganizer, an emitter of nerve forces.  It has the powers of a brain.  It is a reflex center in health and disease.  The sympathetic abdominal nerve alone possesses the power of rhythm.  Every organ possesses rhythm.  In this rhythm of involuntary visceral muscles is doubtless included the factors of initiation, maintenance, and conclusion of visceral absorption and secretion.  The rhythmic, peristaltic muscles massage the glands, inciting their function of secretion and absorption.
    The individual functions of the abdominal brain are numerous and important, viz.: (1) It is the source of new nerves, as it possesses more efferent than afferent nerves. (2) it demedullates nerves; nerves enter sheathed and depart unsheathed. (3) It presides over the rhythm, peristalsis, of visceral muscles. (4) It presides over the absorption and secretion of visceral glands - e.g., the glands lining tubular viscera - and those denominated glandular appendages. (5) The abdominal brain is a giant vasomotor center, controlling the caliber of the abdominal vessels (blood and lymph); it should be termed nervus vasomotorius. (6) It possesses nutritive powers over the nerves passing from it to the periphery. (7) It is the major abdominal reflex center.
    The abdominal brain is not a mere agent of the brain and cord; it receives and generates nerve forces itself; it presides over nutrition.  It is the center of life itself.  In it are repeated all the physiologic and pathologic manifestations of visceral function (rhythm, absorption, secretion, and nutrition).  The abdominal brain can live without the cranial brain, which is demonstrated by living children being born without cerebrospinal axis.  On the contrary the cranial brain can not live without the abdominal brain.  The central idea founded in the abdominal brain should entitle it, in my opinion, to the name vascular or vasomotor brain of the abdomen (cerebrum vasculare abdominale).  It initiates, sustains, and concludes visceral rhythm (the peristalsis of involuntary, visceral muscles) - e.g., in the tractus vascularis, intestinalis. genitalis, and urinarius.  It presides over the absorption and secretion of the viscera - e. g., the mucous glands of the tubular viscera and visceral glandular appendages.  It is evident from the great volume of blood occasionally found in the vastly distended abdominal veins at autopsy that a subject could bleed to death in his own abdominal vessels.  The abdominal brain, the vascular cerebrum, is responsible for this condition, having forgotten, from paralysis. to control the lumen of the vessels.  From the anatomic vascular connection it is impossible to extirpate the abdominal brain from living animals, hence the reports of experimentation accompanied with its extirpation are unreliable.  The abdominal brain is the nervous executive of the abdominal vessels and viscera, the duties of which are to see that the functions of the viscera (rhythm, secretion, and absorption) are faithfully executed.  The abdominal brain assumes practically an independent existence; however, the cerebrospinal axis asserts a controlling influence over it.  For example, in children whose cerebrospinal axis is not completely developed, and at death of  adults, when the cerebrospinal axis has lost its complete control, the intestines will mutiny, assuming a wild, disordered, violent peristalsis, resulting in intestinal invagination.
    The utility of the abdominal brain in practice is important - for example, in postpartum hemorrhage the older practitioners taught that by compression of the aorta the hemorrhage was checked.  This, of course, is an error, as the technique, if it were possible to execute, would not materially affect the bleeding, as ovarian blood-supply would continue.  The physiologic explanation of checking postpartum hemorrhage by pressure over the abdominal aorta is that the manipulation stimulates the plexus aorticus and plexus hypogastricus, which is transmitted to the pelvic brain, where it is reorganized and transmitted over the plexus uterinus to the myometrium, the elastic and muscular bundles of which being excited, contract like living ligatures, checking the postpartum hemorrhage by diminishing the lumen of the vessels.  The irritation, pressure, or trauma of the head of the child on the expanding cervix uteri during the last month of gestation precipitates labor by its effect on the pelvic brain (and consequently on the abdominal brain), by inducing vigorous, persistent uterine contractions.  In feeble labor pains, during uterine inertia, vigorous uterine contractions may be excited by the finger per rectum or per vaginam, irritating or massaging the pelvic brain.  The pelvic brain is palpated with facility, as it is located on the lateral vaginal fornix.  Again, the pelvic brain is subordinate to the abdominal brain; however, the pelvic brain must be intact to allow physiologic orders to pass from the abdominal brain through the pelvic brain to the uterus.  For example, during labor sudden cessation of uterine peristalsis may occur - uterine inertia.  The probable explanation is that as the head passes through the pelvis it traumatizes the pelvic brain, producing temporary paresis from pressure, and partially checks the uterine rhythm.  With the progress of labor the pelvic brain recovers and its dynamics resume.
    The temporary paresis of the pelvic brain does not produce complete paralysis, because a few of the nerves of the plexus hypogastricus (directly from the abdominal brain) pass to the uterus without first entering the pelvic brain.  The abdominal brain rules the physiology of the abdominal visceral tracts.  The methods to utilize the physiology of the abdominal brain in practice are varied.  For example, the mammary gland is connected to the abdominal brain by at least three distinct routes, viz.: (a) via the nerve plexuses accompanying the arteria mammaria and arteria subclavia, whence the route is direct to the abdominal brain; (b) via the nerve plexuses accompanying the arteriae intercostales to the aorta and its plexus, whence the route is direct to the abdominal brain; (c) via the nerve plexuses accompanying the arteria epigastrica superior and inferior to the common iliac, whence the route (plexus) continues on the artery of the round ligament to the plexus uterina, whence the route is direct to the pelvic brain or abdominal brain.  Therefore, by stimulating or irritating the nipple with light friction or massaging the mammary gland, the abdominal brain is reached by the above three routes, and consequently the uterus is induced to contract more frequently, and if the experiments be not repeated too rapidly, the uterine contraction will be more vigorous.  Again, the uterus mav be incited to more frequent and vigorous contractions by administering a tablespoonful of hot fluid, which first emits the stimulation over the plexus gastricus to the abdominal brain, where it is reorganized and sent directly to the plexus uterinus, which incites the uterus to increased peristalsis.   The reverse physiology of the influence of visceral tumors or pregnant genitals stimulating the mammary gland (over the above three routes) is evident.  The tumor or fetus in the genitals rapidly induces the mammary gland to manifest objective disturbances of dimension, circulation, color, palpation, as well as sensory disturbances.
    Practically the uterine nerves originate in the abdominal brain and possess a relative independent existence.  Children are born, expelled, from the uterus after the death of the mother.  Hyrtl, the celebrated Viennese anatomist, reports that during a war with Spain some bandits hanged a pregnant woman.  After she had hung on the gallows for four hours, and consequently was long dead, she gave birth to a living child.  I have observed the giant uterus of slaughtered pregnant cows executing with wondrous precision its rhythm hours subsequent to death and evacuation of uterine contents.  If one will extirpate an oviduct from a human and place it in warm normal salt solution, oviductal rhythm may be maintained by physical stiinulus - e.g., tapping with the scalpel - for some three-quarters of an hour.  If one will chloroform a dog to death and incise the abdominal wall, exposing the intestines, in a room of 70 degrees, the intestines will perform their rhythm, on being tapped with the scalpel, for an hour and a half.  The large urinary vesical apparatus of steers will perform rhythmical movements for half a dozen hours after death in summer temperature.
The anatomic location and the physiologic function of the abdominal brain dignify it into a basic factor in diagnosis from pain.  For example, practically all acute inflammatory pain (localized peritonitis, visceral perforation) or violent visceral irritation (calculus, volvulus, invagination, acute strangulation, obstruction) is first experienced in the epigastric region - i.e., reorganization occurs in the abdominal brain.  This means that all visceral pain, irritation, is first transmitted to the abdominal brain, where it is reorganized and emitted to the abdominal viscera, diffusing the wild, disordered, violent peristalsis (colic) universally in the abdomen, which prevents the localizing of the pain by the diagnostician.  With the progress of the disease the abdominal brain and associated nerve apparatus become accustomed to the new experience and the pain becomes intensified, localized on definite nerve plexuses, whence the pain, tenderness, can be diagnosed by distinct circumscribed localization.  The best example of this view is appendicitis.
    The abdominal brain is the seat of shock.  A blow over the epigastrium, violent trauma to the abdominal brain, may cause immediate shock, collapse, or death.  I performed an autopsy on a subject where invagination of the uterus had killed the patient in two and a half hours.  Death was due to shock in the abdominal brain, transmitted to it over the hypogastric plexus from the traumatized (invaginated) uterus.

CONCLUSIONS AS REGARDS THE ABDOMINAL BRAIN.

    The abdominal brain is a nervous center - i.e., it receives, reorganizes, and emits nerve forces.
The abdominal brain is the nervous executive for the common functions of the abdominal viscera, as rhythm, absorption, and secretion.
    The abdominal brain was originally in function and location a vascular brain - cerebrum vasculare.  Though complicated functions have been added, yet it is still a primary vasomotor center controlling the caliber of the blood-vessels and consequently the volume of blood to viscera, which determines visceral function.
    The abdominal brain is a reflex center in health and disease.
    It is the major assembling center of the abdominal sympathetic.
    The abdominal brain is the seat of shock.  A blow or trauma on it may cause shock, collapse, or death.
    It is the automatic, vegetative, the subconscious brain of physical existence.  It is the center of life itself.
    In the abdominal brain are repeated all the physiologic and pathologic manifestations of visceral function - rhythm, absorption, secretion, menstruation, gestation, ovulation.
    The abdominal brain can live without the cranial brain (and spinal cord), for children have been born alive with no cerebrospinal axis.  Children have been born alive hours after the mother was dead.
    The abdominal brain may be the agent of valuable therapeutics - e.g., in postpartum hemorrhage massage of the aortic plexus will stimulate the abdominal brain to control the blood-vessels of the uterus.  Massage of the aortic plexus will stimulate the abdominal brain to send blood to the viscera, enhancing rhythm, secretion, and absorption, improving constipation and increasing visceral drainage.
    The abdominal brain is the primary agent of rhythmic visceral motion.  A wide office of the physician is to maintain regular visceral rhythm by means of rational therapeutics, as regular habits and exercise, wholesome coarse food, ample fluids, and proper rest.
 

ABDOMINAL BRAIN       Fig.33. An illustration of the sympathetic nerve with abdominal brain.  In this specimen the ureters (calyces, pelvis, and ureter proper) were dilated to the dimensions of an index -finger, the channel of the tractus urinarius presenting no sphincters intact.  This subject possessed a typical abdominal brain (1 and 2) as well as a well-marked pelvic brain (B).  The ganglion hypogastricum (H) is well marked.  This illustration presents fairly well the abdominal sympathetic with their varied anastomoses.  The great ganglionic masses of the abdomen (1 and 2) and pelvis (B) are evident.  It presents a general outline of its nervous vasomotoritis.  I secured this specimen from an autopsy through the courtesy of Drs.  W. A. Evans and O'Byrne.

ABDOMINAL BRAIN       Fig. 34.  This illustration is drawn from a specimen I secured at an autopsy through the courtesy of Drs.  Evans and O'Byrne.  The right kidney was dislocated, resting on the right common iliac artery, with its pelvis (P) and hilum facing ventralward.  The adrenal (Ad.) remained in situ. It was a congenital renal dislocation, and was accompanied with congenital malformations in the sympathetic nerve, or nervus vasomotorius.  1 and 2 is the abdominal brain.  It sends five branches to the adrenal from the right half (2).  Though the sympathetic system is malformed, yet the principal rules as regards the sympathetic ganglia still prevail, viz., ganglia exist at the origin of abdominal visceral vessels, e.g., 3, at the origin of the inferior mesenteric artery; at the root of the renal vessels, HP is no doubt the ganglion originally at the root of the common iliacs (coalesced).  In this specimen the right ureter was 5 inches in length, while the left was 11 1/2.  This specimen demonstrates that the abdominal brain is located at the origin of the renal, celiac, and superior mesenteric vessels - i.e., it is a vascular brain (cerebrum vasomotorius).

ABDOMINAL BRAIN (S.P.).       Fig. 35.  This illustration was drawn from a specimen I secured courtesy of Dr. W. A. Evans.  It is not a typical abominal brain, on account of the peculiar method of emission of the adrenal nerves (C) 10 on the left side and 14 on the right side.  The right side represents duplicate renal and spermatic arteries.  This is a typical subject to demonstrate the abdominal brain as a vascular brain (cerebrum vasculare or cerebrum vasomotorius), as it is located at the origin of the abdominal visceral vessels, vis., renal, celiac, and superior mesenteric arteries.  B, splanchnic major; H, splanchnic minor; D, renal ganglia.  This specimen presents what I term the swan’s-neck-shaped ureters (2).  Note ureteral valves (5 and 6) and dilated ureters.  The bladder and prostrate are hypertrophied.  The ureters present a network of nerves surrounding them.  Observe the large renal ganglion on the ventral surface of the renal artery at D.

ABDOMINAL BRAIN - CEREBRUM ABDOMINALE.       Fig. 36.  This illustration was drawn from a carefully dissected abdominal brain.  I dissected the tissue under alcohol.  The relations and proportions are those of life, being drawn by accurate measurements. 1 and 2, abdominal brain.  Observe the nerves which the adrenals receive: Sp, splanchnic major; DG, ganglion diaphragmaticum; GR, renal ganglia; Ad, adrenals; LS, lesser splanchnics; RA, arteria renalis; H, hepatic; G, gastric; and Sp, splenic artery. The hook fixes the ganglion of the phrenic artery which I term ganglion arteriae phrenicae.

ABDOMINAL BRAIN.       Fig. 37.  This illustration drawn from a cadaver, illustrates the location, relation, and radiating plexuses of the solar plexus, or abdominal brain (71 and 72), which is built around the major visceral arteries, the celiac (73, 74, 75), superior mesenteric (1 6), and renal (88) arteries; hence it dominates the visceral function as to vascularity (blood and lymph), peristalsis, absorption, and secretion.  The clinical manifestations of the abdominal brain are coextensive with that of the abdominal viscera.  This ganglion of the first magnitude presents radiating plexuses to all the abdominal viscera, presenting an exquisitely balanced and poised nervous mechanism, controlling vascularity (blood and lymph), peristalsis, absorption, and secretion. 76 and 185, splanchnic major; ll0, 111, ganglia ovarica.  The body from which this dissection was drawn possessed wide, flat nerves, as is noted by the majestic ganglion - the abdominal brain or cerebrum vasoinotorius ; 69 is the left vagus.

GANGLION CELLS IN THE ABDOMINAL BRAIN.       Fig. 38.  Drawn from a microscopic section of the abdominal brain.  Observe that the cells lie in connective tissue nests, i. e., the ganglion cells are ensconced in separate chambers of connective tissue.  The prolongations of the cells, i. e., the conducting cords, pass hither and yon, forming a network.