STRUCTURE AND FUNCTIONS OF THE SPLEEN. 519 



ractcristio of the lymph and abundant in the lymphatic glands. The remaining fibrous 

 substance consists entirely of capillary blood-vessels and lymphatics, with minute corpuscles, 

 much smaller than blood-corpuscles, varying in size from about 1-GOOOth to l-7000th of an 

 inch, of spherical form, and usually corrugated on the surface. These lie in great numbers 

 in the meshes of the sanguiferous capillaries; and the minute lymphatics are described by 

 Dr. E. as connected with the splenic corpuscles, and apparently arising from them. Lying 

 in the midst of the parenchyma are found a large number of bodies, of about a third of a line 

 in diameter, which are evidently in close connection with the vascular system : these have 

 long been known as the Malpighian bodies of the spleen, after the name of their discoverer ; 

 but since his time, their existence has been denied, or other appearances have been mistaken 

 for them. According to Dr. E., they in all respects resemble the mesenteric or lymphatic 

 glands in miniature, consisting as they do of convoluted masses of blood-vessels and lym- 

 phatics, united together by elastic tissue, so as to possess considerable firmness: and they 

 further correspond with them in this, that the lymph they contain, which was quite trans- 

 parent in their afferent lymphatics, now becomes somewhat milky, from containing a large 

 number of Lymph-globules. 



684. In regard to the functions of the Spleen, great uncertainty exists. It 

 appears from the foregoing account of its structure, that it may be regarded 

 as an organ of duplex character, and probably of double function. The cel- 

 laled structure maybe considered as a muhilocular reservoir, capable of great 

 distention, and lined with a continuation of the inner membrane of the vein; 

 receiving blood, on the one hand, from the veins of the interior of the organ, 

 and transmitting it onward to the Vena Porue ; and on the other hand, acting 

 as a reservoir for the venous blood of the abdomen, when, from any cause, 

 its passage into the Vena Cava is obstructed. The splenic parenchyma, on 

 the other hand, must be regarded as a complex Lymphatic tissue, essentially 

 resembling that of the lymphatic glands, but differently arranged. In those 

 animals in which it predominates, as in Man, the artery is large ; on the other 

 hand, where the collated structure is most developed, as in the Herbivora, the 

 Vein is very large, and the artery comparatively small. Nothing completely 

 analogous to a Spleen is found in Invertebrated animals ; and from the absence 

 of the Lymphatic system in them, it is evident that the parenchymatous por- 

 tion can have no existence as such. Something analogous to the cellated por- 

 tion of the Spleen, however, exists in the venous system of many Cephalopoda: 

 and this circumstance is an additional proof of the duplicity of the character 

 of this remarkable organ. 



685. Out of the numberless theories of its operation, which have been at 

 different times brought forwards, the one which seems best to account for its 

 cellated structure, is that which regards it as a sort of diverticulum or reser- 

 voir ; which may serve to relieve the Portal Venous system from undue dis- 

 tention, under a great variety of circumstances. This system is well known 

 to be destitute of valves ; so that the Splenic vein has free communication 

 with the whole of it. Hence the Spleen will be a ready diverticulum for the 

 venous blood, when the secreting action of the Liver is feeble, so that the 

 Portal circulation receives a partial check ( 832). That any cause of con- 

 gestion of the Portal system peculiarly affects the Spleen, has been proved by 

 experiment ; for after the Portal Vein has been tied, the Spleen of an animal, 

 which previously weighed only 2 ounces, has been found to weigh a pound 

 and a quarter, or ten times as much. Now it is evident that congestion of 

 the Portal system is liable to occur, when the alimentary canal is distended 

 with food ; and this from two causes, the pressure on the Intestinal veins, 

 and the quantity of fluid absorbed by these veins. Hence it may be conceived, 

 that the Spleen, by affording a reservoir into which the superfluous Venous 

 blood may be directed, serves an important purpose in preventing congestion 

 of other organs. From the observations of Mr. Dobson,* it appears that the 



* London Med. and Phys. Journal, Oct. 1820. 



