LIM, T. P. K. 
itself or of its perfusing blood. On the other hand, peripheral con- 
trol is believed to depend upon efferent impulses arising in cutaneous 
thermoreceptors, so that the relevant "peripheral temperature" is 
that of the skin. 
On the basis of this general premise, the relationships between 
the temperature control and detector mechanisms may be inves- 
tigated, the principal aim of the study being to evaluate the relative 
roles of central and peripheral temperatures in the initiation of 
thermal panting in the warmth and shivering in the cold. 
The roles of central and peripheral temperatures in the initi- 
ation of thermal panting or shivering have never been adequately 
defined. Some investigators stress the importance of central control, 
others of peripheral control, and some admit the possibility that 
perhaps both are involved. One fact which can be regarded as firmly 
established is that so called "pure central panting" can be produced 
by local heating of the hypothalamus in the anesthetized cat (Magoun 
et al., 1938). In addition, recent data indicate the existence of "pure 
central shivering" which can be produced by local cooling of the 
hypothalamus in the unanesthetized cat (Kundt, Bruck, and Hensel, 
1957) and in unanesthetized dogs (Hammel and Hardy, 1959). 
Nevertheless, a great deal of uncertainty exists as to whether cen- 
tral and peripheral temperatures interact to initiate thermal 
panting or shivering. The reasons for such ambiguity are partly due 
to (1) the erroneous choice of rectal or colonic temperature as 
representing the central (brain) temperature, in particular, during 
transient states of induced hypothermia or hyperthermia, (2) the 
inherent difficulty of dissociating central and peripheral tempera- 
tures in the intact animal, and (3) the poorly defined criteria for 
the onset of thermal panting or shivering. 
Thus it appears that the key for the successful answer to the 
problem is to overcome these three shortcomings revealed in the 
previous studies. In other words, (1) the brain temperature has to 
be measured directly in the vicinity of the hypothalamus instead of 
measuring rectal or colonic temperature, (2) the central and peri- 
pheral body temperatures have to be dissociated to allow a clear 
distinction between the action of two regional thermal stimuli and 
(3) the onsets of thermal panting and shivering must be defined. 
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