ROLE OF THE PROSENCEPHALON IN SHIVERING 
be relatively normal until the environmental temperature plum- 
meted. Conversely, if the rabbit with lesion "D" could shiver but 
not vasoconstrict cutaneously, then it is conceivable that in an 
enfeebled condition its body temperature would fall despite the 
neural "drive" to produce heat by muscular shivering. That their 
animals, studied but for five days post- surgery, were enfeebled 
seems evident from their statement (1914) that "we have never 
observed that an originally disturbed heat regulation later became 
normal, but we have often witnessed the reverse." This completely 
contradicts the latter-day findings, exemplified by the work of Hess 
(1957), that functional deficits produced by hypothalamic lesions 
become attenuated the longer the preparation lives after surgery. 
Figure 12 secondly shows schema of four lesion preparations 
that were considered by Clark, Magoun, andRansonto implicate the 
anterolateral hypothalamus in body temperature regulation against 
heat stress and the posterolateral hypothalamus in regulation against 
cold stress. Admittedly in a later review Ranson and Magoun (1939) 
stated that their observations on shivering were fragmentary, but 
this work (which essentially confirms the work of Isenschmid and 
his co-workers but had the advantage of beingbased on observation 
of animals fully recovered from surgical trauma) is still widely 
quoted with respect to the neurogenesis of shivering. Their work 
does not conflict with our results if it is accepted that their lesion 
"C" does not include the dor somedial posterior hypothalamus and 
their lesion "D" affects both dorsomedial and dorsolateral hypo- 
thalamic tissue as well as the more pronounced ventrolateral 
destruction. 
Thirdly, two lesions from one of Keller's (1959) investigations 
are shown in Figure 12 . Their dogs, maintained for long periods 
after surgery, could shiver and maintain normal body temperature 
even when placed in a 5 C environmental temperature for several 
hours. The hypothalamic lesions spare only the dorsal posterior 
hypothalamus, thus suggesting that shivering involves the dorso- 
medial neurons and vasoconstriction the dorsolateral neurons. 
Time does not permit a more detailed comparison of our re- 
sults with divergent results in the literature. If it is accepted that 
shivering will not return in the early post-operative period after 
any hypothalamic lesion, and that cutaneous vasoconstriction 
343 
