258 VETERINARY PATHOLOGY. 



Enibryoiiic. 



Coiniccfiz'e. 



Sarcoma. 



Endothehoiua. 



Hypcnicphyoma. 



Placciiloma. 

 Epithelial. 



Carcinoma. 



Epitlielioma. 



Adenoma. 



Hypernephroma. 



Planeentoma. 

 Adult and Embryonic. 



Any and all tissues. 



Teratoma. 



The term "tnnior" was formcrlv used to indicate any swelling 

 in animal tissues. They, more than any other pathologic entit}^ 

 have been studied and investigated by scientists, and yet little 

 is known of their pathology. With the present limited knowdedge 

 it is impossible by definition to clearly differentiate them from 

 scmie other pathologic conditions. They have been defined as 

 new growths of tissue deyeloping independently in any tissue 

 of the animal body and atypical in structure and function. Also 

 they are non-inflammatory growths of new tissue, persistent, 

 independent of the surrounding structures, atypical in structure 

 and function. A more concise idea can be formulated by think- 

 ing of them as parasites, that is, the\- are new growths of tissue 

 tliat develop in or upon the animal body at the expense of the 

 animal, and are subject to the same pathologic conditions that 

 the normal tissues are, as degeneration, necrosis, etc. 



Frequency. — Tumors are of frcfpient rjccurrence. Thev 

 are more cijmmon in dogs ijarticularh- aged ones than in other 

 animals. Of I'-T animals presented in the daily clinic at the 

 Kansas Cit}- A'eterinary college during one college sessiim, 12 

 were aft'ected with tumors. 



The frec|uencv of tumors in animals treated in the Berlin, 

 Dresden, and Munich veterinary colleges for an average period 

 of seven years is shj,wn by the follov/ing: 



Of 86,613 diseased horses, 1,113 suffered from tumors, or 1.3 per cent. 

 Of 85,537 diseased dogs, 4.020 suffered from tumors, or 4.7 per cent. 

 Of 4.972 diseased cattle, 102 suffered from tumors, or 2 per cent. 



Structure. — Tumors are composed of cells and usually, an 

 intercellular substance. The cells ma\ be siinilar to norinal em- 

 bryonic cells or to adult cells. The embryonic tumor cells differ 

 from normal embryonic cells in that the former have no ten- 

 dency to become matured while the latter have. The accom- 

 panying cut shows a section of a sarcoma composed of embrv- 



