ROLE OF THE PROSENCEPHALON IN SHIVERING 
the data in Table VI, it was concluded that both the intensity of heat 
production (shivering) and the heat retention capacity could vary in 
intact cats over rather wide ranges and independently of each other. 
It was therefore decided to compare the ratio of shivering/resting 
VO and rectal temperature variations in 0.5 C air of the animals 
with hypothalamic lesions to the mean and range of data presented 
in Table VI rather than to data collected on each animal prior to 
surgery. This was done because it was felt that declines in shiv- 
ering capacity and heat retention capacity would only be significant 
if they resulted in a ratio of VO shivering/resting below 2.0 and 
in a decline of rectal temperature /unit time in C to 5 C air 
above 0.07 C min, i.e., below the two lower limits of the ranges 
listed in Table VI. 
Five animals typify the results and the extent of neural tissue 
destruction in these cats is illustrated in Figures 8-11. In Table 
VII the various metabolic determinations and somatic observations 
are listed for cats No. H , H , H and H , F and F , ST 24, ST 
25. Additionally the table shows the animals with similar lesions 
and similar metabolic responses to the cold stresses. Cats No. H , 
H , H , H and H , F , F , F , F , F , ST 19 and ST 38 shivered 
in response to the cold stresses andtheVO ratio shivering/resting 
ranged for these animals from 2.1 to 2.6. The lesions in these 
various cats would embrace all anterior and posterior hypothalamic 
tissue except the dorsomedial region of the posterior hypothalamus. 
In Cat No. F the lesion extended somewhat into this region (Fig. 
8), and in this cat shivering was present but somewhat feeble^ the 
ratio of shivering/resting VO being 1.9. In Cat No. ST 25 there is 
even greater encroachment of the lesion into this region (Fig. 10), 
but shivering was present, if somewhat more feeble. In this cat the 
ratio of VO shivering/resting was 1.7, 1.7, and 1.8 on successive 
days tested. In Cat No. H, the dorsomedial region of the posterior 
hypothalamus was destroyed to a far greater extent (Figure 11), 
and this cat did not shiver during the cold stress, the ratio of VO 
cold stress/resting being 1.2 and 1.0 on successive days tested. This 
cat was subjected to a third day of testing in order to take moving 
pictures of the animal's ability to piloerect and assume a huddled 
posture while at a low, non-shivering rectal temperature. On this 
day it was obvious that this cat could make appropriate behavioral 
responses to low body temperature in that atthe conclusion of each 
331 
