226 DISEASE IN WILD MAMMALS AND BIRDS 
Glycogenic and fatty conservation is a function pos- 
sessed by both zoological classes as are the detoxicating 
and bile-producing powers. However it is highly prob- 
able that urea and creatin in metabolism is not cared for 
by the avian liver as it is by the mammalian, judging by 
the researches of Paton and of Richet. 
Fat Deposits. 
The care of fat by the liver is very well shown by 
examining the incidence of fatty metamorphoses through 
the various orders. In the first place Mammalia show a 
slightly higher percentage of fatty change than do Aves 
and should show a greater difference were it not for the 
large number of cases in two orders of the latter. Among 
mammals, lemurs, rodents and marsupials store fat in the 
liver more than other orders but in, the second and third, 
it is chiefly the carnivorous varieties that have this 
property. Just why the slothful herbivorous lemurs 
should be first on the list is not evident especially since 
the grain-eating Ungiilata are least apt to present fatty 
livers. With tliis exception, mammals with plentifully 
available hydrocarbons in their diet are most apt to show 
its deposit in the organ under discussion. Among the 
birds the gallinaceous varieties stand far ahead of all 
others, the passerines following next. Galli show the con- 
dition in association with acute infections, chronic dis- 
eases and in health. Unless there be distinct reason for 
it at autopsy, it may almost always be said to be normal. 
Passeres, especially the smaller forms, frequently come 
to autopsy with such excessively large livers, and 
indeed "svith a very large pad of abdominal fat, and 
nothing else, that one is compelled to look upon this over- 
burdened organ as incapacitated by the deposit. These 
two orders increase the percentage value for the birds. 
Striges, Anseres, and Accipitres also show a good number 
of cases but there is among the Aves no such clear rela- 
