DISEASES OF THE SPLEEN. 255 



volume. It lias movements of contraction and expansion, 

 which are slow and rhythmical. The spleen may be exter- 

 minated in animals and man without any serious ill effect. 

 Hypertrophy of some of the lymphatic glands, and red 

 marrow of bones follows, and these tissues probably take 

 on a vicarious function. The blood coming from the spleen 

 is said to contain a larger number of white cells than that 

 entering it. 



In diseases in which the spleen is enlarged, the blood 

 contains a large excess of white cells. 



Diseases of the spleen are very rarely, if ever, diagnosed 

 in the horse during life, though various pathological changes 

 are not uncommonly met with in making post-mortem 

 examinations. 



Enlargement of the ^^Spleen. — Enlargement of the spleen 

 is of rare occurrence, except when depending on abnormal 

 growths, as lymphadenoma and melanosis. 



Lymphadenoma. — Lymphadenoma of the spleen is some- 

 times found as greyish masses of about the size of a cherry, 

 and sometimes still larger. 



These formations in the spleen are said by some to be 

 accompanied by leucocythsemia (Xiu-/.og, white ; -/.uroc,^ a cell ; 

 and a//xa, blood) in many cases. 



There are no diagnostic symptoms by which these tumours 

 can be recognised during life. 



They are, however, not unfrequently accompanied by 

 anaemia, anorexia, and loss of flesh. 



When examined microscopically, we have found these 

 tumours of the spleen to be composed of an adenoid reti- 

 culum, or network of fine homogeneous fibrils, the meshes 

 of which are completely occupied by lymph corpuscles. 



Other Morbid Growths of the Spleen. — Cancer, melanotic 

 growths, and lardaceous degeneration are sometimes met 

 with after death, but cannot be diagnosed during life. 



