CENTRAL AND PERIPHERAL MECHANISMS 
likely that hypothalamic rather than skin receptors playedthe major 
role in central shivering. 
Series VII - Peripheral Cooling 
In the next series, we wished to determine whether peripheral 
shivering could be initiated. The trunks of 10 animals were cooled 
for an average period of 19 minutes (range: 5 to 34 m in), while 
their brain temperatures were kept between 37.6 C and 40.2 C 
by carotid warming. All animals began to shiver with in nine minutes 
(range: 0.5 to 20 min) at the mean surface temperature of 29 C to 
30 C, although the average visceral temperature was not altered 
or only sligjitly reduced (Table II). Interestingly enough, a compar- 
ison of the surface temperature thresholds between whole body' 
cooling and peripheral cooling Series disclosed no statistical dif- 
ference (p>0.5) which implies that the shivering observed in whole 
body cooling is primarily of reflex origin. From these i-esults it 
is concluded that shivering can be produced in anesthetized dogs by 
peripheral thermal stimulus alone when the hypothalamic tempera- 
ture is maintained at the range of 38.0 C to 40.0 C. 
Series VIII - Repetitive Cooling and Teimination of Shivering by 
Central and Peripheral Warming. 
The data acquired in the above three Series in the cold (Table 
II) indicate that both central and peripheral shivermg exist and that 
shivering observed in whole body cooling is predominantly of peri- 
pheral origin. To supplement these findings, four animals were 
repeatedly cooled and rewarmed centrally as well as peripherally. 
All animals responded to such a repetitive procedure. 
To explore further the interrelationship between central and 
peripheral temperatures during shivering, central shivering was 
