STUART, D. G. 
clips. Great attention was directed to the postoperative care of each 
animal. The rectal temperature was kept at 36 C to 38 C by 
appropriate alterations in environmental temperature. For the first 
2 to 3 weeks after surgery each animal was tube fed with frequent 
testing for the recoveryof licking and swallowing reflexes. Care was 
taken to keep each animal clean and dry and given daily periods of 
exercise. 
Twenty-one animals recovered from the above procedure, and 
once they had regained their pre-operative weight by spontaneous 
eating, their responses to cooling were studied. One animal died 
at 12 hours, one at 5 days, one at 8 days and one at 10 days after 
surgery. Three animals died during the coiirse of heat stress tests 
administered 4 days after surgery. The resting oxygen consumption 
rate of 18 of the 21 cats which recovered was determined 13 to 132 
o 
days after surgery at an environmental temperature of 20 C to 
25 C. They were then exposed to an environment of C to 5 C 
temperature, and 15 minutes after such exposure their oxygen con- 
sumption rates were determined for a further twenty minutes of 
exposure. Rectal temperature was maintained throughout these 
determinations. 
Control experiments consisted of measuring oxygen con- 
sumption rates and rectal temperatures of unoperated cats in the 
warm (25 C) and cold (0 C to 5 C) environment. 
If the animals with hypothalamic lesions had oxygen consumption 
rates and rectal temperature responses that fell within the un- 
operated cat range of responses, they were sacrificed immediately 
after the test, their brains fixed in formalin and sectioned every 
80 microns, and alternate sections stained with buffered thionine. 
If any of the animals did not have control unoperated responses 
they were tested at least twice more at varying lengths of time 
after the first test before being sacrificed. 
In subsequent figures illustrating the extent of various brain 
lesions, a schematic midsagittal diagram will show the rostrocaudal 
extents on each side of the brain. Such diagrams are based on re- 
construction of the extent of the lesions from the buffered thionine 
slides. Additionally two to three film negatives of buffered thionine 
slides are presented to illustrate the dorsoventral and medial lateral 
extents of tissue destruction. 
328 
