140 HUMANE TREATMENT OF ANIMALS USED IN RESEARCH 
and conversion to use as animal maintenance quarters. Shortages 
of storage space and other service facilities of the animal quar- 
ters also were noted. Progress in enlarging animal facilities, 
while marked over the past few years, has kept up with the demand 
only by "borrowing" space from areas originally planned for 
supporting activities. As a direct result these necessary support 
activities have been slighted in some institutions. 
In most instances the animals were clean and well cared 
for. However, of 57 institutions, 16 had no thermostatically 
controlled heating system. Of 58 institutions, 21 had air condi- 
tioned quarters; but 22 did not and 16 had only a portion of the 
rooms air conditioned. Table 10 indicates the number of air 
changes per hour in animal rooms in 49 reporting institutions. 
Response to questions concerning air handling in the 58 institu- 
tions surveyed revealed that air was not recirculated in 747., 
was filtered in 567., and was pressure controlled in 147.. 
In the opinion of the site visitors, expenditures for 
thermostatically controlled heating, air conditioning and air 
change equipment would be worthwhile investments for a large 
number of institutions. 
Future research will undoubtedly require better control 
of the laboratory animal environment. Much of the fundamental 
research on disease problems is now concerned with chronic 
diseases. Animals used in these programs will have to be main- 
tained for long periods of time. Such animals must be kept free 
of extraneous diseases. Where the environment is controlled 
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