TUMOUBS. 



425 



We find no record of cyst-bearing and dentigerous 

 cysts having been observed in cattle practice. 



Fig 85. — Pneumatic Aspirator, used for the removal of the contents of 

 fluctuating tumours without admission of air. 



Clinically, tumours are of minor importance in com- 

 parative pathology. Their diagnosis comprises determi- 

 nation of their nature. It must be first decided whether 

 the swelling is solid or contains liquid. Certain of the 

 cancers, especially of the medullary form, may seem to 

 contain fluid. Generally the grooved exploring needle 

 or the suction trocar (fig. 84) may be used, and the 

 material brought out with it will often give us a clue 

 to the nature of the case. Signs of malignancy must 

 be sought for, especially the diseased condition of lym- 

 phatic glands. There seems to be in some animals 

 a tendency to hypertrophy of certain tissues, hence, 

 not infrequently, a number of fibrous or osseous tumours 

 appear, simultaneously however, which contrasts with the 

 consecutive growth in cases of malignance; also the 

 growths all occupy one kind of tissue. Some swellings 

 depend on inflammations, and must be considered exu- 

 dates in a more or less altered condition. Our guide in 

 determining the nature of these, and distinguishing them 

 from hypertrophies, must be their origination with an 

 inflammatory attack, also their course to a standstill 

 or decrease when inflammation ceases. The position of 

 the growth and its physical characters will generally 



