306 DISEASES OF CATTLE. 



admittedly, at some important point, failed of their purpose. Since 

 the value of this chapter depends chiefly upon its practical character, 

 which in turn is measured by its aid in diagnosis, prognosis, and 

 treatment, the old but important clinical division is here adopted. 



Tumors are either malignant or benign. The essential difference 

 between the two classes is that while benign tumors depend for 

 their ill effects entirely upon their situation^ malignant Tieoplasms 

 wherever located inevitahly destroy life. The clinical features of 

 each group are in many cases sufficiently marked to distinguish 

 them. 



MALIGNANT TUMORS. 



(1) These are invariably pernicious, and from the beginning tend 

 to destroy life. 



(2) The cellular element predominates; therefore they grow 

 rapidly. 



(3) Possessing no capsule, i\\&y infiltrate surrounding tissues. 



(4) They infect adjacent lymph glands. 



(5) They recur even after complete removal. 



(6) They give metastasis; that is, they become drsseminated in 

 different organs. 



(7) Their presence develops a progressive emaciation. 



BENIGN TUMORS. 



(1) These in and of themselves do not tend to produce death. 



(2) As the cellular element is not liable to j)redominate, they grow 

 slowly. 



(3) They are encapsulated, and when diffuse do not infiltrate sur- 

 rounding tissues. 



(4) They do not infect adjacent lymph glands. 



(5) They do not recur after complete removal. 



(6) They do not manifest metastasis. 



Benign tumors, though harmless, may, by the accident of their 

 location, indirectly produce death. Mere pressure on the brain 

 substance of an otherwise innocent tumor, compression of the blood 

 supply for vital organs, growth in such manner as to cause obstruc- 

 tion in the alimentary tract or pressure upon nerves, may cause 

 death, or, prior to death, so combine the effects of anemia (deficiency 

 of blood), starvation, and pain, with its consequent restlessness, as 

 to produce a veritable cachexia (condition of general ill health). 



On the other hand, a malignant tumor in its primary growth may 

 so implicate a vital organ as to destroy life before metastasis can 

 occur or even before cachexia can develop. Thus, to the untrained 

 observer, environment may so operate as to cause these two classes 

 of new growths to simulate each other. The boundary lines may 



