1336 PHYSIOLOGY 



contraction may be induced by stimulation of the splanchnic 



nerves. 



FUNCTIONS OF THE SPLEEN 



The structure of this organ suggests that the splenic cells must 

 exercise a constant influence on the blood which surrounds them, and 

 that this influence is not purely of a chemical nature. In the liver and 

 kidneys, which exercise so powerful an effect on the composition of 

 the blood passing through them, the proper cells of the organs are 

 separated from the blood-stream by the capillary wall. Microscopic 

 examination of the cells of the splenic pulp shows us that these are 

 full of particles of brown pigment or fragments of red corpuscles 

 (Fig. 550). In many cases of infectious disease, such as recurrent 



FIG. 550. Cells from a scraping of the spleen. (KoLLiKER.) 

 A, splenic pulp-cell containmg red blood-corpuscles, b (Jc nucleus) ; B, 

 leucocyte with polymorphous nucleus ; c, pulp-cell containing disintegrated 

 red corpuscles ; D, lymphocyte ; E, giant cell ; F, nucleated red corpuscles ; 

 G, normal red corpuscle ; E, multinuclear leucocyte ; J, eosinophile cell. 



fever, the splenic cells are observed towards the end of the attack to 

 be full of the organism spirillum which is the cause of the disease. 

 In fact, these cells are so arranged that they can take up solid par- 

 ticles held in suspension in the blood-plasma. We must indeed look 

 upon the spleen as the great blood-filter, purifying the blood in its 

 passage by taking up particles of foreign matter and effete red cor- 

 puscles. The process of phagocytosis, which was described under 

 the cellular mechanisms of defence (p. 1145), is in the spleen a normal 

 occurrence. 



A function has also been assigned to the spleen in the formation 

 of red blood-corpuscles, but the evidence is not sufficient to determine 

 whether such a process occurs normally. 



Chemical analysis of the spleen reveals the presence of a large 

 number of what are called extractives, such as succinic, formic, 

 butyric, and lactic acids, inosit, leucine, xanthine, hypoxanthine, 



