TEMPERATURE OF THE BODY AND ITS REGULATION 1229 



any part of the central nervous system, so that it would be possible to speak 

 of a heat centre in the same way as we speak of a respiratory or vaso-motor 

 centre, is doubtful. Many observers have found that injury to the corpus 

 striatum causes a rise of temperature associated with increase both in heat 

 production and in heat loss. On the other hand, injury to or pathological 

 lesions of the pons Varolii offcen lead to an increased production of heat in the 

 body, which is not compensated for sufficiently by heat loss, and so causes 

 death by hyperpyrexia. It has been suggested that the thermogenic 

 centre, i. e. that responsible for regulating heat production, is situated at a 

 lower level in the nervous system than the thermotaxic system, i. e. that 

 which presides over and determines the balance between heat production and 

 heat loss. The observations of Meyer and Barbour, that local cooling of the 

 corpus striatum causes increased respiratory exchanges and heat production, 

 while warming has the reverse effect, certainly point to a localisation of the 

 thermotaxic centre in this part of the central nervous system. The centres 

 for heat loss must be placed in the medulla, at any rate so far as concerns 

 control of heat loss by alterations in the blood supply to the skin or in the 

 secretion of sweat. The facts at our disposal are however too meagre to 

 warrant any definite localisation of the heat-regulating function in the 

 central nervous system, or any such accurate analysis of the regulating 

 function as has been just suggested. 



In many warm-blooded animals the ability to maintain a constant tem- 

 perature is not fully developed until some time after birth. Pembrey has 

 shown that in the guinea-pig and chick, in which the nervous system is 

 fully functional at birth, the heat-regulating mechanism is also completely 

 adequate, whereas animals such as rats, pigeons, or the human child, which 

 are born in a helpless condition, only acquire the power of regulating their 

 own temperature some time after birth. As we should expect, the develop- 

 ment of the power of regulating heat production runs pan passu with the 

 acquisition of control by the nervous system over the muscles of the body. 



