ROLE OF THE PROSENCEPHALON IN SHIVERING 
tested five and nine days after surgery than in those tested one 
and three days after surgery. Cat No. 7 gave evidence of a slow 
tremor interspersed between grosser arrhythmic twitches, and 
Cat No. 8 had a faster tremor that, by palpation, resembled shiv- 
ering. If the body temperature of the preparations were slowly 
lowered simply by decreasing the environmental temperature to 
25 C, no somatic responses to cooling were evident even when the 
body temperatures fell to the same levels as those following im- 
mersion in cold water. When the animals were rewarmed by im- 
mersion in waim water (40 C), the movements disappeared when 
the body temperatures reached 36 C to 38 C. If the rewarming 
was rapid (immersion in 50 C water), the animal's somatic 
responses were similar to those seen during rapid cooling. This 
suggests that the response the decerebrate animal makes to rapid 
cooling and rewarming is a non-specific avoidance response to a 
nocioceptive stimulus. This concept is supported by the fact that 
similar somatic responses of briefer duration were evoked by 
other "unpleasant" stimuli such as rectal thermometer insertion, 
pinching the hindlimb or fast rotation of the animals. 
Metabolic and rectal temperature determinations. As shown in 
Table 1, the oxygen consumption rate before cooling for Cats 5, 6, 
7, 8, and 10 lies within the normal range for unoperated cats of 
weight range 2 to 4 kg. Cats 17 and 22 had lower oxygen consumption 
rates in keeping with their enfeebled condition. There was little 
variation between the animals in somatic responses during cooling. 
However, the variation in somatic movements during the second 
VO determinations was quite marked. Cats 5 and 6 making few 
somatic responses, Cat 7 making intermittent gross kicks, Cat 8 
maintaining the tremor evoked by the cooling stress, and Cats 10, 
17, and 22 becom ing quite hypotonic after cooling stresses, although 
making violent movements during such stresses. The variations in 
oxygen consumption rate of the animals after cold exposure paral- 
leled the variations in their somatic responses. During the oxygen 
consumption rate measurements after cold exposure, the cat had 
cold wet skin and the rectal temperatures of Gats 5, 6, 7, and 8 
continued to fall during the 20-minute period of the determinations. 
This was not the case with Cats 10, 17 and 22. The rectal tempera- 
ture of Cat 10 rose 0.6 G during the post-cold VO determination, 
but the rectal temperature of this cat was only 27 C at the beginning 
303 
