84 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



Lab. Chow 



Peanut Oil 

 20% 



Newol 

 20% 



Lab. Chow 



Newol 

 20 °/. 



Fig. 1.— Effect of cold and diet on the saturation of fat in hamster and rat. "Newol" is the 

 trade name of a saturated commerical cooking fat. 



change of iodine number may well have physiological significance, its relationship 

 to the onset of hibernation has yet to be demonstrated. 



Brown fat. While considering the subject of fat, it is perhaps necessary to men- 

 tion brown adipose tissue. Brown fat occurs in many parts of the body, but the por- 

 tion located between the scapulae is often referred to as the "hibernating gland." 

 Rasmussen's-^ careful work showed, however, that this tissue occurs in many ani- 

 mals that do not hibernate, including monkey, dog, cat and rat. Fontaine-^ has most 

 recently defended this tissue as being of possible importance to the hibernating state. 

 It has been shown that extracts of this tissue from woodchucks and ground squir- 

 rels^° and hedgehogs^^ injected into rats caused a lowering of metabolism. Such 

 non-specific effects, as Wertheimer and Shapiro^- state in their review of animal fat, 

 prove only that heterologous brown fat contains some substance that depresses me- 

 tabolism. The lack of specificity is emphasized by the report of Nitschke and Maier^^' 

 that extracts of lymphatic tissue from thymus, spleen and lymph nodes also caused 

 a drop in metabolic rate. In this regard it should be emphasized that it is not known 

 whether depression of metabolism is a cause or a result of the hibernating state. The 

 observation that extracts of brown fat from woodchucks of unknown sex contained 

 androgen^* is of interest but does not seem to implicate the tissue in the problem of 

 hibernation. 



The stumbling block appears to be that the function of brown fat is very imper- 



