CENTRAL AND PERIPHERAL MECHANISMS 
that your experiments prove them. I would be much happier if you 
had sectioned the fifth nerve bilaterally, for one thing. Another thing, 
I am not willing to accept a respiratory rate of one hundred as equal 
to panting. Much more important than rate as far as panting is con- 
cerned is amplitude, and I would be much more happy to accept a 
small amplitude respiration. 
DR. LIM; Then, what is your definition of panting? 
DR. CLARK: If I am defining panting, I do not use rate at all. 
The cat and the dog have to open their mouth, retract the angle of 
the mouth, and move the tongue. That is a matter of semantics. 
Then, you said skin and brain are essential elements. Dr. 
Blatteis of our group has evidence that there are possibly some 
temperature sensing elements in the iliac vessels, and I do not 
know of any work myself that rules out the possibility of temperature 
sensing elements in several other places. I doubt if they are there, 
but I think that the data are not in. 
As for your hypothalamic temperatures, Magoun, in his dia- 
grams, has only indicated a position with reference to a sagittal 
plane, but gives no data on whether it is medial or lateral. Again, 
however, I think you are probably right. 
DR. LIM: Our areas were within three to four millimeters of 
the center linewhichis very close to the medial line. Oir definitions 
of panting and shivering are arbitrary, depending on our different 
workers. I do not know whether we have a clear-cut definition to 
make everybody happy on this, but I doubt it very much. 
DR. IRVING: Should you not have some indication of the function 
of the panting, namely, that it was dissipating heat in an additional 
degree? I think that is implicit in what Dr. Clark is saying. 
DR. LIM: Usually the tongue is protruded and, of course, the 
surface of the tongue is very important in the dissipation of heat. 
In most of the animals we studied their tongues were protruding. 
And we think this definition of respiration rate of lOO/min is ade- 
quate for our purpose. 
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