Chap, v.] NUTRITION. 649 



lower. In such cases there can be little doubt that the con- 

 dition is due to diminished metabolism and diminished heat 

 production. 



One of the most marked phenomena of starvation is the 

 fall of temperature, which becomes very rapid during the last 

 days of life. The lowered metabolism diminishes the produc- 

 tion of heat, and the lowered temperature in turn still further 

 diminishes the metabolism. Indeed the low temperature is a 

 powerful factor in bringing- about death, for life may be much 

 prolonged by wrapping a starving animal in some bad con- 

 ductor so as to economize the bodily heat. 



§ 432. Effects of Great Heat. As we said above, the regu- 

 lative heat mechanism is unable to withstand the strain of too 

 great an external heat or too prolonged an exposure to a great 

 but less degree of heat. The temperature of the body then 

 rises above the normal ; and it has been observed that the 

 temperature is more easily raised by warmth than depressed 

 by cold, at least when neither are very intense. When either 

 in this way by external warmth or through pyrexia the tem- 

 perature of the body is raised some 6° or 7° above the normal, 

 to 45° or thereabouts, death speedily ensues. The chain of 

 events thus leading to death has not been as yet clearly made 

 out, and most likely the events do not take exactly the same 

 course in all cases ; but we shall probably not go far wrong 

 in attributing death to the fact that the high temperature 

 hurries on the metabolism of the several tissues, of some more 

 than others, at such a spendthrift rate that their capital is soon 

 exhausted. We have seen, § 301, that too warm blood pro- 

 duces dysjmcea, and soon exhausts the metabolic capital of the 

 respiratory centre. Too warm blood similarly hurries on the 

 beats of the heart : an explosion of the contractile substance is 

 each time prematurely brought on before a sufficient quantity 

 of explosive substance is accumulated, each stroke becomes 

 more and more feeble as the rate is quickened, the beats be- 

 come irregular, and finally cease. Either of these two events 

 alone and certainly both together are enough to bring the 

 working of the bodily mechanism to an end ; but other tissues 

 beside the heart and the respiratory centre are suffering in the 

 same way, notably the rest of the central nervous system. 

 This too is being hurried on unduly in its inner changes, so 

 that not only consciousness is lost and other objective manifes- 

 tations of nervous action go wrong or fail, but that regulative 

 grasp of the central nervous system on the tissues of the body 

 at large is loosened, and tumult takes the place of order. 

 Whether this or that sign of disorder comes to the front, 

 whether for instance convulsions take place, would appear to 

 depend upon the exact turn taken by the abnormal events. In 

 heat-stroke, more commonly known as sun-stroke, the essential 



