USES OF THE SPLEEN. 



735 



the venous trunks unite to form the splenic vein, which, like the other 

 tributaries of the portal system, is destitute of valves ; some of the 

 veins of the spleen pass on to the stomach, and join with its veins. 

 The lymphatics of the spleen, divided, as usual, into a superficial and 

 deep set, are by no means numerous. The mode of origin of the deep 

 set is unknown. It has been supposed that the cavities of the Malpig- 

 hian bodies communicate directly with the lymphatics, but this has 

 not been proved. The spleen is supplied with comparatively few 

 nerves, which are derived from the sympathetic system. 



The splenic pulp, with its granules, nuclei, and nucleated cells, must 

 be the seat of rapid nutritive and formative processes. The bulk of 

 this organ increases in a marked manner during, and especially to- 

 wards the end of, the process of digestion ; an enlargement due, not 

 only to an increase in the quantity of blood contained in the splenic 

 vessels at that period, but also to a simultaneous increase in the quan- 

 tity of all the microscopic elements of the pulp itself. Even the Mal- 

 pighian corpuscles increase in size, and, it is said, in number, after 

 the digestive process is completed. Their diminution in both respects, 

 in states of exhaustion and innutrition preceding death, may account 

 for their existence in Man having been denied. In starving animals, 

 the Malpighian bodies are certainly few and small, or they may even 

 disappear; whereas they become larger and more abundant in those 

 which are well fed. The colored cells, or altered red blood-corpus- 

 cles, are likewise increased in mumber in highly nourished conditions 

 of the body. 



Since the colorless nuclei and nucleated cells of the spleen bear 

 some resemblance to lymph-corpuscles in an early stage of develop- 

 ment, and since, in certain conditions, such corpuscles, then considered 

 as nascent white blood corpuscles, are found in large numbers in the 

 blood of the minute veins and larger venous trunks, the spleen has 

 been regarded, by Hewson and others, as one of the seats of formation 

 of the white corpuscles of the blood, probably by the successive sub- 

 division of old cells, thus acting, as it were, as a large lymph-gland, 

 directly connected with the venous system. In certain cases of en- 

 largement of the spleen white corpuscles are found in extraordinary 

 number in the blood of the splenic vein, so as even to alter its color, 

 and the number of these white corpuscles in the blood generally in- 

 creases to such an extent that their proportion to the red corpuscles 

 may be as high as 1 to 10. This condition has been named leuccemia 

 or leucocythcemia, meaning white blood. 



It has also been supposed (Kolliker, Funke, Billroth) that the 

 spleen may be the seat of formation, in some yet undetermined way, 

 of commencing red corpuscles. The small, bright yellow corpuscles 

 inclosed in larger cells may undoubtedly be traced in the spleen, 

 through a series of intermediate phases, into the ordinary flattened 

 disc-like red corpuscle ; but that these appearances indicate an upward 

 development is doubtful. On the contrary, it is suggested that the 

 red blood-corpuscles, having for a time performed their functions in 

 the circulation, and having lived, as it were, their natural life, may 

 really undergo disintegration and destruction in the spleen (Kolliker). 



