30 DISEASE IN WILD MAMMALS AND BIRDS 
present studies, that there is an unqualified relationship 
between the size and expected longevity of an animal and 
its pathological lesions. 
The immediate surroundings and the management of 
captive animals have a very direct and important bearing 
upon the mortality and perhaps upon the incidence of 
morbid processes but probably not upon the character of 
the latter. A full knowledge on the part of the personnel of 
a zoological society concerning the habits and habitat of 
every animal in their keeping is essential, to which must 
be added a group of interested keepers. In engaging the 
last, it should not be forgotten that certain men 
have ''a way" with animals and that others cannot 
manage themselves. 
The enormous literature at the disposal of the 
naturalists permits executive officers to formulate a plan 
of housing and feeding with fair accuracy for each kind 
of animal, but of course it is rarely possible to obtain in 
sufficient quantity the natural food {e.g., ants for ant- 
eaters). In so far as food is concerned it seems that with 
a few exceptions like the one just mentioned, the substitu- 
tions made at the zoological gardens are nearly 
satisfactory. The elements in which the captive diet is 
poor are the inorganic salts and vitamins since Dr. 
Corson- White, some of whose work is included in a later 
chapter, has shown that for those animals which our 
statistics indicate as most prone to have rickets and osteo- 
malacia, the available phosphorus and calcium are low, 
and one vitamin was also below the desired quantity. In 
this regard, however, I am not at all convinced that diet 
alone will suffice to explain these degenerative osseous 
diseases ; I shall take this up more fully later. Careful 
inspection of all food should be made and cleanliness 
(sifting of cereals, protection of meat from flies, etc.), is 
indispensable. The mortality among our camivora has 
materially decreased since the horse meat after butcher- 
ing was placed in covered galvanized iron pans. There 
