HEMINGWAY, A. 
a 5-day recovery period from a trauma of surgery, there is an 
increase in the ability of animals to resist cold. These observations 
while somewhat limited in scope, and contradictory to the majority 
of the results of others, would lead to the rather important general- 
ization that a controlling mechanismfor defense against cold occurs 
in the brain stem below the hypothalamus. In order to investigate 
this question further and to extend the work to other animals, a 
study of chronic decerebrate cats has been made in our laboratory. 
In these animals, the entire forebrain above a plane extending from 
the superior colliculi to the mammillary bodies is isolated from the 
brain stem by transection followed by removal of a 2 mm wedge of 
midbrain tissue. Considerable nursing care is required for these 
animals for the preventionof hypo- andhyperthemiaand cage sores. 
Hand feeding is required. However, with this time-consuming effort, 
the animals can be maintained for periods of several days to several 
months. These animals have been studied carefully by the methods 
already described. It has been found that in two of nine animals, a 
tremor only remotely resembling shivering can be induced by cold 
exposure and stopped by warmth. However, this tremor is valueless 
in protecting an animal against cold. The tremor does not raise the 
oxygen consumption rate and does not prevent a fall in rectal 
temperature in the cold. Professor Philip Bard of Johns Hopkins 
University, who has made extensive studies of the chronic decere- 
brate cat and has been interested particularly in the temperature 
regulation impairment caused by decerebration, has also observed 
this cold-induced tremor in the chronic midbrain preparation (1958). 
The occurrence of the cold-induced tremor in the chronic decere- 
brate cat, while it serves no useful purpose in temperature regu- 
lation, does raise the question of the extent in the central nervous 
system of the controlling mechanism for body temperature regu- 
lation. 
Lesions of the central nervous system. The transection tech- 
nique for separating completely the central nervous system into two 
unequal parts with no intracerebral or intraspinal nervous connection 
between the two parts has served a useful purpose in anatomical 
localization of the level in the central nervous system for control 
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