STUART, D. G. 
hypothalamus is sufficient for an animal to shiver effectively in the 
cold. However, it is not possible on the basis of these experiments 
to designate a more precise or limited region as being responsible 
for the production of shivering. 
In Table VII cold test A was only used when the mechanical 
breakdown of the cold test B refrigerator system occurred. In such 
tests it was not possible to gain an indirect picture of an animal's 
heat retention capacity. However, in cold test B,by measuring both 
oxygen consumption and rectal temperature while exposed to C 
to 5 C air, this was possible. As shown in Table VI, the range of 
rectal temperature drop /unit time in C to 5 C air was 0.02 C 
to 0.07 C/min for intact cats. Table VII shows this figure was .13 
C/min for Cat No. F , .13° C/min for Cat No. F , and .33 C/min 
for Cat No. H . Additionally, Cats No. F and H had figures of 
over .13° C/min and Cats No. F , F and F , ST 19 and ST 38 fig- 
ures of less than 0.07° C/min.'^ince Cats No. F and F and H 
and H had bilateral lesions that effectively destroyed the lateral 
tuberai and posterior hypothalamic regions and Cats No. H , F , 
F and F , ST 19 and ST 38 had lesions that destroyed only the 
ventrolateral tuberai and posterior hypothalamic tissue, it would 
appear that the effective retention of heat is a function of the dorso- 
lateral tuberai and hypothalamic tissues. Such a conclusion is 
further supported by destruction of this tissue being evident in Cat 
No. F (Fig. 9). It would appear that the dorsolateral anterior 
hypothalamus is not involved in heat retention in that in Cat No. H 
the dorsolateral anterior hypothalamic tissue was destroyed yet 
the animal both shivered effectively and had a rectal temperature 
rise/unit time in C to 5 C air of .01 C/min. 
Although the animals with lateral and dorsolateral hypothalamic 
lesions appeared to have a diminution in heat retention capacity in 
C to 5 C air, by indirect determination, this was not obvious in 
25 C air. That is to say, these animals had, at this higher temper- 
ature, rectal temperatures and resting oxygen consumption rates 
within the normal range. 
No systematic attempt was made to study temperature regula- 
tion disturbances in the immediate postoperative period. Table VIII 
lists the responses of three cats to heat and cold stresses 4 to 46 
days after surgery. Four days after surgery the three animals had 
338 
