552 PHYSIOLOGY CHAP. 



particularly from the work of Gurwitsch (1893) and Zelensky 

 (1891). The former made 10 minute comparative analyses of the 

 blood of the carotid and splenic vein in dogs ; the latter determined 

 on dogs and rabbits the effect of the peritoneal injection of splenic 

 extract. On counting the corpuscles and estimating the haemo- 

 globin with Hiifner's spectro-photoineter, before and after injection, 

 there was invariably a marked rise in both, whence the author 

 concluded that " splenic infusion contains the products necessary 

 to the regeneration of the blood." 



The lymphoid tissue of the spleen, which consists essentially of 

 Malpighian corpuscles or nodules, is a lymphapoietic or leucocyte- 

 forming organ analogous to the lymph follicles and glands 

 (Virchow). This is plain from the fact that the blood of the 

 splenic vein contains many more leucocytes than the blood of the 

 splenic artery (Kolliker and Hirt, Bizzozero and Salvioli). In the 

 blood of the splenic vein the ratio between the number of the 

 leucocytes and that of the erythrocytes is as 1 : 60 ; in the 

 arterial blood, as 1 : 2260. In splenic leucaemia the lympha- 

 poietic function of the spleen is enormously increased, so that it 

 sends out a great quantity of leucocytes into the blood torrent. 

 This fact coincides with a corresponding enlargement of the organ, 

 due to hyperplasia of the lymphoid tissue. 



It is to the wealth of leucocytes in the spleen and their 

 special metabolism that we must refer the fact that the chemical 

 compounds of the splenic pulp abound in nuclein and its deriva- 

 tives, i.e. adenine, xanthine, hypoxanthine, guanine, and uric acid. 

 Lecithin, jecorin, cholesterin, and inosite are also present. The 

 alkaline reaction of the splenic pulp becomes acid after a short 

 time, owing to the development of fatty acids, among which are 

 succinic, formic, acetic, and lactic acid. The constant presence of 

 uric acid in the fresh spleen should be noted, even in these 

 herbivorous animals whose urine does not contain it. Horbaczewski 

 (1889) states that when a fragment of still living spleen is dipped 

 into blood freshly extracted from an animal, it induces the forma 

 tion of considerable quantities of uric acid. This proves the spleen 

 to be an important, if not the sole, organ in the formation of uric 

 acid, which, as we shall see elsewhere, is derived from the nuclein 

 bases present in large quantities in the splenic pulp. 



Since the spleen is a contractile organ, its volume undergoes 

 great variations. Normally it swells during the digestive period, 

 reaching its maximum five hours after meals ; it remains turgid 

 for some time, and eventually regains its normal volume. This is 

 the effect of an active hyperaemia analogous to that which is 

 simultaneously exhibited by the mucosa of the alimentary cord, the 

 pancreas, and the other glands attached to the digestive apparatus. 

 This coincidence in hyperaemia points to the probability of the 

 active intervention of the spleen in the chemical phenomena of 



