HEAT DISSIPATION FUNCTIONS FOLLOWING 
EXPERIMENTAL ANTERIOR HYPOTHALAMIC LESIONS 
IN CATS 
George Clark 
Physiology Division 
U.S. Army Medical Research Laboratory 
Fort Knox, Kentucky 
For the past decade or so there has been a remarkable uni- 
formity in the usual discussions of the central nervous mechanisms 
for the control of the various processes by which a homeotherm 
maintains its body temperature within normal limits. The basic 
theory has been that there are separate regions for integration of 
those activities which enable an animal to increase the rate of heat 
loss and for those which promote heat conservation. This proposal 
was originally made by Myers (1913). Among the important papers 
which led to partial localization of these centers are those of Ott 
(1884, 1891, 1895), Isenschmid and Schnitzler (1914). Nikolaides and 
Dontas (1911) and Keller and Hare (1932). Figure 1 is one method of 
expressing the dual center concept. In a poikilotherm the body 
temperature as shown by the solid line is a function of the environ- 
mental temperature, while the true homeotherm (dash dot line) can 
maintain its body temperature constant over a wide range of environ- 
mental temperatures. Only in extreme heat does its body tempera- 
ture rise. Only in extreme cold does its body temperature drop. 
Animals in which the region where heat loss activities are activated 
has been destroyed should react as well as normal animals in a cold 
or cool environment; however, their body temperature should rise 
progressively on exposure to a mild heat load (as indicated by the 
dash line). Finally animals with ablation of the region where heat 
maintenance activities are integrated should tolerate heat loads as 
well as normals but should not be able to withstand cold (as indic- 
ated by the dotted line). The current dual center theory which implies 
exact localization of the two areas has been thought to be validated 
by the work of Ranson and his co-workers. The usual reference is 
to a review by Ranson in the volume on the hypothalamus (Volume 
20, 1940) of the series sponsored by the Association for Research in 
Nervous and Mental Disease. The basic data in this review were 
taken from four papers, two of which must be considered in some 
detail in order to summarize the current localization concept. I have 
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