INTRODUCTION 31 
are many problems of feeding, too numerous to be cov- 
ered in a survey of this sort, which must be solved, and 
it is a credit to superintendents that this they have 
studied carefully. 
There are two problems in the management of 
animals upon which much difference of opinion exists, 
namely the heating of houses and the material of which 
cages are made. It seems to be the practice in many 
gardens to keep animals very warm. Dr. Chalmers 
Mitchell states unqualifiedly that adult animals do 
not have to be kept warm, and that even an equable 
temperature is not demanded, variations in temperature 
having a distinctly stimulating eif ect. However he main- 
tains that they should be kept dry and must be supplied 
with a shelter. This is in accord with the experience at 
the Philadelphia Garden, since for many years we have 
allowed access to the open air all winter to every animal 
that could stand it. A large group of macaques has now 
lived entirely in an open "band stand" cage for nine 
years with a lower mortality than in the rest of the 
monkey collection, which is permitted to go indoors some 
of the time. Occasionally one in poor health is frozen to 
death, and healthy ones may lose fingers, toes, or a part 
of the tail, but the general condition is so much improved 
that they present an attractive exhibit to visitors. Unless 
a storm be of great severity, wild animals are usually 
indifferent to it although they may seek their shelter. 
Snow apparently is no source of fear to them, and many 
enjoy playing in it. The general principles of the enclosure 
should be proper lighting, free access of air, dryness and 
shelter in time of storm, the last so arranged that the 
sleeping place is well protected. Appropriate arrange- 
ments should be made for nocturnal animals, regardless 
of their visibility to visitors, if their preservation is 
of importance. 
The hygiene of communicable disease has influenced 
everyone to use concrete and metal for cages. These sub- 
