40 DISEASE IN WILD MAMMALS AND BIRDS 
experience is needed for definite practical comparisons. 
This applies to thyroid and pituitary disorders and to the 
vague conditions we have at times been obliged to call 
marasmus or inanition. 
Some attention has been given to the study of diets for 
the wild specimens of our Garden, but no systematic 
observations have been made or records kept upon purely 
physiological subjects. Reference will be made at appro- 
priate places to accepted comparative physiological facts, 
but our statistics permit additions to such knowledge only 
in a limited manner and in isolated instances. Doctor 
Corson-White has very ably summarized the diet, ali- 
mentary tract and physiology of the zoological groups 
with the pathology as found in our records. 
A word might be added here as to the destruction of 
animals by injury from fighting and harassment by 
others in the cage. Fighting doubtless causes death, 
especially when males are together, but it is our experi- 
ence that in cases of traumatic death search should 
always be made to see if the resistance of the dead animal 
had not been reduced by some disease. This is well illus- 
trated in birds. Very frequently a specimen will come to 
autopsy with its head feathers plucked out, or with a bill- 
thrust in the wing or pelvic region. Such birds are not 
infrequently suffering from malaria, or heavy intestinal 
parasitism or from organic disease whereby the resist- 
ance and self-preservatory power has been decreased. 
The foregoing survey of the approach to our subject 
reveals the multiplicity of factors which affect the study 
of comparative pathology. No one of them can be entirely 
omitted, no one is without some effect upon the origin and 
expression of disease, and no one is fully understood. 
Yet it is to be hoped that a study of our material, accumu- 
lated under routine conditions and uninfluenced by any 
experimental procedures, will demonstrate the natural 
response of various zoological groups to morbific 
agencies. Perhaps reactively some of the modifying 
