CH. xxill.] THE SPLEEN. 325 



through the skin, the number of leucocytes in the blood is almost 

 immediately increased. 



Removal of the spleen is not fatal ; but after its removal there 

 is an overgrowth of the lymphatic glands to make up for its 

 absence. 



(2.) It forms coloured corpuscles, at any rate, in some animals; 

 in these animals, cells are found in the spleen similar to those we 

 have described in red marrow, and called hcematoblasts. In these 

 animals, if the spleen is removed, the red marrow hypertrophies. 



(3.) There is reason to believe that in the spleen many of the 

 red corpuscles of the blood, those probably which have discharged 

 their office and are worn out, undergo disintegration ; for in the 

 coloured portions of the spleen-pulp an abundance of such cor- 

 puscles, in various stages of degeneration, are found, and in 

 those cases of disease in which the destruction of blood-corpuscles 

 is increased (pernicious anaemia) iron accumulates in the spleen as 

 in the liver. It was formerly supposed that the spleen broke down 

 the corpuscles and liberated haemoglobin, which, passing in the 

 blood of the splenic vein to the liver, was discharged by that organ 

 as bile-pigment. But this is not the case; the disintegration does 

 not proceed so far as to actually liberate haemoglobin ; there is no 

 free haemoglobin in the blood-plasma of the splenic vein. 



(4.) From the almost constant presence of uric acid, in larger 

 quantities than in other organs, as well as of the nitrogenous 

 bodies, xanthine and hypoxanthine, in the spleen, some share 

 in nitrogenous metabolism may be fairly inferred to occur in it. 



(5.) Besides these direct offices, the spleen fulfils some purpose 

 in regard to the portal circulation with which it is in close 

 connection. . From the readiness with which it admits of being 

 distended, and from the fact that it is generally small while 

 gastric digestion is going on, and enlarges when that act is 

 concluded, it is supposed to act as a kind of vascular reservoir, or 

 diverticulum to the portal system, or more particularly to the vessels 

 of the stomach. That it may serve such purpose is also made 

 probable by the enlargement which it undergoes in certain affec- 

 tions of the heart and liver, attended with obstruction to the 

 passage of blood through the latter organ, and by its diminution 

 when the congestion of the portal system is relieved by dis- 

 charges from the bowels, or by the effusion of blood into the 

 stomach. This mechanical influence on the circulation, however, 

 can hardly be supposed to be more than a very subordinate 

 function. 



Influence of the Nervous System upon the Spleen. When the 

 spleen is enlarged after digestion, its enlargement is due to two 



