LIM, T. P. K. 
DR. HEMINGWAY: It is possible, though, to tie out both common 
carotids. I have seen this done in a dog, and the dog is perfectly 
happy for a while, except for some atrophy of the facial musculature. 
He will live for a few days without showing any effect, thus indicating 
the vertebral circulation is extensive enough to substitute for the 
carotid circulation. 
MR. ADAMS: I wonder if Drs. Clark and Hemingway would be 
willing to accept an index of panting based on respiratory, evapora- 
tive heat losses, rather than on respiratory volume or pattern? 
DR. HEMINGWAY: Like your water loss, it goes up very 
abruptly. If you will notice, when a dog starts to pant, he first takes 
a few deep breaths; then all of a sudden there is an abrupt rise in 
respiratory rate and a drop in tidal volume at the same time. If you 
measure the water outputthat goes up abruptly, too. It should also be 
noted that it is also possible to stop shivering without any change in 
skin temperature by just warming the anterior hypothalamus. A 
number of people have done this. No change at all in skin tempera- 
ture is observed. 
MR. EAGAN: Is it possible thatthere is a sufficient association 
of the heat loss center and the heat conservation center, that you 
could get, with a suitable choice of conditions, a pre-panting hyperp- 
nea at the same time as shivering? 
DR. LIM: I do not know, but I accept it for the sake of the dis- 
cussion. I do not know how clearly the two centers are defined. 
DR. CLARK: I would say that the center for heat conservation 
is fairly well defined andthat the center for heat dissipation is much 
less clearly defined than we would be led to believe from reading the 
literature. 
MR. EAGAN: I was thinking of the functional association. 
DR. CLARK: I would not expect simultaneous shivering and 
panting because where you have opposing centers, you are going to 
have interconnecting inhibitory and excitatory fibres. 
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