THERMORECEPTOR PHYSIOLOGY 
DR. FREEMAN: Dr. Hammel, when he places his thermode, 
merely has a plate which he attaches to the skull under anesthesia 
and allows the skin to grow over it. 
DR. HENSEL: Yes. 
DR. FREEMAN: Now, when he wants to do an experiment, he 
sterilizes the skin over this plate and forces the thermode down 
into the hypothalamus for the duration of the cooling and heating 
period, and when he is through with the animal for the day, he pulls 
it out and puts the animal away. 
DR. HENSEL: Yes. 
DR. FREEMAN: Now, he says that over a period of time there 
may be some damage to the hypothalamus. 
DR. HENSEL: I would not agree with him. We had the thermode 
in the cat for half a year, and we have one cat in which we did the 
implantation five times, each time for half a year. It is now three 
years and the cat is quite as happy as in the beginning. So I do not 
think that there would be a serious damage. 
DR. FREEMAN: You would leave yours in, though, for the full 
period of time? You do not take them out? 
DR. HENSEL: No. 
DR. FREEMAN: You leave it in once it is there? 
DR. HENSEL: It remains for six months in the cat, and you can 
repeat this several times and go on without any disturbance. 
DR. FREEMAN: One other technical question: how do you 
prevent over-heating with your device; that is, when you want to 
warm the animal, what level dod you choose for your inflow tem- 
perature as an adequate stimulus? 
DR. HENSEL: As yet, we studied only the cooling. We were just 
interested in this effect because the effects during heating are more 
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