NERVOUS PATHWAYS 
DR. CLARK: I know the C7 spinal cat becomes exquisitely 
sensitive . 
DR. CHATONNET: I know the sensitivity against posterior 
pituitary extract. 
DR. FREEMAN: Have you discussed your results with Dell or 
Stutinsky or Bonvallet, who worked similarly? 
DR. CHATONNET: Yes. 
DR. FREEMAN: They came, I believe, to the conclusion that 
the hypophysis played a major role in regulation in spinal dogs. 
DR. CHATONNET: I do not beUeve that the hypophysis plays an 
important role in regulation in spinal dogs, at least in the capacity 
of thermogenesis that I studied. Bonvallet and Dell (1946) observed 
that hypophysectomy or the section of the supraoptico-hypophyseal 
tractus deprived the spinal- dog of the ability to maintain his central 
temperature for exposure to 20 C to 22 C. Injection of posterior 
pituitary extract again set up this ability. The authors explain the 
fact at least partly thus: impairment of water metabolism by 
hypophysectomy lessens the efficiency of the remaining thermo- 
genesis in that animal. But they have not measured the metabolism 
of their dogs. One can also suppose that the essential disturbance 
concerned heat loss regulation by vasomotor control. In any way, 
the thermogenetic capacity of the C7 spinal dog is poor and 
does not depend on any "per se" thermogenic hormonal control, but 
on residual muscular activity. However, such a long-acting vascular 
factor should produce slow adaptation to environmental change. In 
the Bonvallet and Dell experiments the reactions were very fast. 
Our chronic spinal dogs and the dogs whose spinal cords have 
been destroyedcontroltheirtemperature in a limited range of exter- 
nal temperatures according to the extent of innervation abolished, 
but in this range their regulation is immediate and the thermogene- 
sis involved is steady from day to day. 
DR. FREEMAN: Did you compare your results with theirs? 
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