CHAP, v.] NUTRITION. 857 



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 is very intense. When either in this way by external 

 warmth or through pyrexia the temperature 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, 371, that too warm blood 

 produces dyspnoea, 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 become 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 manifestations 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 condition of 

 which seems to be a rapid rise of the temperature of the body 

 owing to a sudden failure of the thermotaxic mechanism, the 

 symptoms vary. Sometimes the heart suddenly gives way, at other 

 times the respiratory centre seems to be more directly affected ; 

 sometimes convulsions make their appearance, but more commonly 

 death takes place through a comatose condition of the brain, an 

 initial phase of excitement of the central nervous system being 

 not unfrequently witnessed. 



Mammalian muscle, it will be remembered, 84, becomes rigid 

 at about 50 ; but death probably always occurs before that higher 

 temperature is reached by the blood, so that a sudden rigor mortis 

 from heat (rigor caloris) cannot be regarded as a factor in death 

 from exposure to too great heat. But should that temperature 

 ever be reached by the living body, all we know leads us to infer 

 that a sudden rigidity of the whole body would at once put an 

 abrupt end to life; to suppose that a human body can truly 



F. n. 55 



