468 DISEASE IN WILD MAMMALS AND BIRDS 
Incidence of Tumors. 
Examination of the table, (21) from the standpoint 
of differential percentage reveals that mammals have 48 
tumors giving an incidence of 2.58 per cent, whereas birds 
have 44 newgrowths equivalent to 1.23 per cent. Were 
it not for the high figures for one single variety of bird 
(Undulated Grass Parrakeet) this value for Aves would 
be still lower. At all events our figures would indicate 
that the mammal is at least twice as productive of neo- 
plasms as is the bird. In our material the latter class has 
had a better chance than Mammalia to show its 
susceptibility since there have been nearly twice as 
many autopsies. 
AVithin the classes the comparative figures have less 
value because of the smaller and varying numbers. Such 
high percentages as are sho^\^l by the elephants and 
armadillos cannot be taken as indicators for their orders 
since too few specimens were examined. Judging by 
orders with more than one hundred autopsies the rodents 
stand at the head of the list followed by the marsupials 
and carnivores. It is interesting that the animal nearest 
to man, the monkey, and with greatest number of autop- 
sies in its zoological class has the lowest tumor incidence. 
Psittaci lead the avian orders, followed by the Fulicariae, 
but as there are but tliirty-five autopsies upon these, the 
second place rightly belongs to the Anseres. All the 
principal orders are represented but the only one of 
importance is the leader. The Psittaci are very prone to 
have tumors in the renal area, sometimes of the kidney, 
at others of the adrenal and occasionally of the sex 
glands. Some remarks have already been given to this 
matter in the sections devoted to the kidney and genitalia 
but it ^\ill be discussed again under tumor morphology. 
Among these ninety-two animals, one bore multiple 
tumors, a Jaguar {Felis onca) with adenomata of the 
liver and uterus and angiomata of the mesentery. Care- 
