STUART. D. G. 
of this determination. Cats 17 and 22 had rectal temperatures of 
33.2 C and 32 C respectively at the beginning of this post- cold 
stress determination, similar to the beginning rectal temperature 
of 32.5 C of Cat 7. However, Cat 7 had a decline in rectal temper- 
o • 
ature of 3.0 Cduringthe 2 0-minute post-cold stress VO. determin- 
• 2 
ation biit an elevation of VO of +32% over the pre-cooling stress 
level, in keeping with its intermittent somatic activity during this 
period. In contrast. Cats 17 and 22 were quite hypotonic after cold 
exposure, and their oxygen consumption rate determinations were 
less than 50 percent of that of Cat 7; yet the rectal temperature of 
o 
Cat 17 fell only 0.8 C and that of Cat 22 remained unaltered during 
this period. 
Comments 
Shivering was defined above as cold-induced rhythmic muscular 
activity resulting in a two to four-fold increase in oxygen consump- 
tion rate and limb tremor frequencies of 9 to 11 cycles/sec On the 
basis of this definition none of these decerebrate animals shivered 
in response to cooling. Even Cat 8, who displayed a fast tremor 
that appeared on cooling, disappeared on warming and by palpation 
and independent observation resembled shivering, could not be said 
capable of shivering in that there was no appreciable oxygen con- 
sumption elevation during the period of tremor. Additionally, Cat 
8 and all the other cats displayed similar somatic responses during 
rapid cooling and rapid warming and no responses during slow 
cooling and slow warming. Thus, these limited observations suggest 
that the decerebrate cat is capable of making similar somatic 
responses to rapid cooling, warming, and other nocioceptive stimuli 
and also has the neurological '"substrate" that if activated produces 
tremulous motions that are not related to temperature regulation. 
This latter concept is based on the fact that tremulous activity was 
seen in two of the seven cats (No.'s 7 and 8). This may be explained 
by the resultsof Jenkner andWard(1953), Folkert and Spiegel (1953) 
and Wycis, Szekely and Spiegel (1957), who produced tremulous 
activity in anesthetized monkeys and cats by electrical stimulation 
of the reticular formation over a wide region of the midbrain, pons 
304 
