A STUDY Ix\ M our. ID AXD X () R .M a L P II Y S I u L G V. 143 



AfTEK IllltlTATIO-N. 

 First Period — 

 Rise of temperature of body in 1 \ lunirs 0".8, in 1 liour OO.Gl = t'. 

 Q = W X t' X sp. h. = 2ii.i> X 0.G4 X 0.75 = 9.84 = heat added t.i reserve. 



179.8G43 = heat dissipated hourly 



Haarly production of heat 189.704,3 



Second Period — 

 Fall of temperature in 1^ hours 0^.8, in 1 hour 0^.6 = t'. 

 Q= W X t' X sp. h. = 20.0 X O.G X 0.7.T = 9.225 = heat taken from reserve. 



225.0797 = heat hourly di-ssipated. 

 9.225 = heat taken from reserve. 



Hourly production of heat 215.8547 



SUMMAIIY. 



ITourly production liofore irritation 245.7li7.3 



Hourly production during irritation 189.704:! 



Hourly production after destruction 215.8547 



The first of these experiments is a simple one, performed in the manner already 

 indicated. It will be noted that during the period of irritation there was a derided 

 reduction in the hourly production of heat amounting to 22 per cent. In the 

 second experiment tlic diminution in tlie rate of heat production following the 

 salting was curiously enough also 22 per cent. Tliere was in the second experi- 

 ment an attempt to destroy the centres after tlie period of irritation ; neither of 

 them, however, was destroyed. The rise of heat production tliat followed the 

 operation was distinct, but did not equal the previous fall, the whole amount of 

 heat produced not being as great as before the skull Avas opened. Probably there 

 was in tKis case during tlie last calorimetrical observation paresis of one centre, 

 and irritation of the other. 



The experiments which have just been detailed are in accord with those pre- 

 viously reported* in which the brain was locally destroyed. Tli(> results of the 

 entire series, comprising 22 consecutive concordant experiments, tire summed up 

 in the following proposition : — 



Destruction of tlic first cerebral cojirolidion la the <hrj postrrlor to and in the 

 vicinity of the sulcus cruciatus is folloired at once hi/ a vcrij decided increase of 

 heat production, tchiht after irritation of the same nervous tract tliere is a decided 

 decrease of hieat production. 



Whatever may be the exact nature of the proven relation between the region 

 of the brain under discussion and thermogenesis, there is one very important point 

 which is not absolutely determined by my experiment.s, namely, as to the per- 

 manency of the effects induced. There are three experiments bearing upon the 

 subject, in wliicli only one convolution was wounded ; in two of these trials the 

 increase of heat production was seemingly maintained twenty-four hours after the 

 operation, but in the third it was not kept up. There are also three experiments 

 in which the two centres were involved ; in only one of these is there any show 

 of permanency in the increased heat production. In the most thoroughly watched 

 of the experiments the early formation of an intra-ventricular clot may have 



