TUMORS OF THE SPI.EEN. 



Secondary. Delay of blood favors. Sarcoma : horse, cattle, dog. Car- 

 cinoma : horse, dog. Melanoma : comtQon and large in gray and white 

 horses, rupture, external melanosis. Angioma: horse, ox. Lymphadend- 

 ma : horse, ox, external adenoma. 



The different tumors of the spleen are usually secondary. The 

 intimate structure of the organ, the peculiarity of the circulation 

 through the pulp cavities, and the delay of the blood in the pulp 

 spaces, predispose it in a very especial manner to the growth of 

 neoplasms, the germs or bioplasts of which are carried in the blood. 



Sarcoma. In the horse sarcomata have been found in the 

 spleen secondary to similar tumors in the other parts of the ab- 

 dominal and thoracic cavities. They may attain to any size, 

 from a pea to the closed fi,st and, in exceptional cases, of a mass 

 which practically fills and distends the abdominal cavity. 



In the cowan encephaloid sarcoma in the .spleen, weighed nine 

 pounds and was associated with similar formations in the lymph 

 glands generally of the abdomen and chest. 



In the do£- also sarcomata are common in the spleen. 



Carcinoma. These are found in the /lorse in connection with 

 similar primary tumors, as in the case of the .sarcomata. They 

 are at times extremely va.scular and soft, and at other times they 

 are hard and fibrous (scirrhus). 



In the dog- secondary cancer of the spleen is comparatively 

 common. 



Melanoma. Black pigment tumors are especially common in 

 gray and white horses. Their common seat is on the black, 

 hairless portions of the skin (anus, vulva, perineum, tail, sheath, 

 mamma, eyelids, lips, etc.), and secondarily in the lymph glands 

 and spleen. In the latter they may grow to an extreme .size, 

 Wehenkel having mentioned one .specimen of 60 pounds. Its 

 surface is marked by uneven, rounded black swellings, the entire 

 organ, indeed, seeming to be a conglomerate of these masses. 

 The intimate structure is that of a sarcoma, so abundantly 

 charged with black pigment granules that these appear to make 

 up the greater part of the ma,ss. 



Rupture of the.se neoplasms with the escape into the abdomen 

 562 



