88 PBINCIPLES OP VETEBINAEY SUEGEBT 



excess and lying dormant, are stimulated by some agent or 

 other, leading to the growth, of the tumor. 



3. Hereditary influence. 



4. Irritation and injury. 



5. Predisposition (melano sarcoma of the gray horse). 



6. Age, sex, species, food. 



What observations tend to show that food and age a/re etiolo- 

 gical factors in the development of tumors f 

 The statistics of various veterinary colleges show that in 

 carnivora (dog) carcinoma are more frequently seen than in 

 herbivora (horse, ox); also, that carcinoma have never or but 

 rarely been noticed in dogs below the age of two years. 



What does the clinical examination of a tumor consist off 



By inspection, learn its seat and size, whether circum- 

 scribed or diffused, the nature of its cutaneous covering and 

 that of the adjacent skin. By palpation, study its fixedness 

 or mobility, consistency and state of the regional lymph 

 glands, whether painless or not. Learn the age of the 

 patient, and, if possible, the history of the development as to 

 its rapidity. Finally, to settle doubts as to the nature of the 

 neoplasm, a microscopical examination of a bit of the tumor 

 may, although rarely, be called for. A general examination 

 of the patient for constitutional disturbances should always 

 be made. 



What reasonable deductions can be made from the data ob- 

 tained by the clinical examination of a tumor f 

 1. The seat of a tumor or the nature of the tissuas in 

 which it originated suggests the' following : Tumors in the 

 testicles or mammary gland are likely to be carcinomata, 

 botryomycoma in the testicular cord, fibromata, papillomata 

 and carcinomata in the skin, in the subcutis lipomata and 



