ANIMAL HEAT. 493 



ably only intermittently active, coming into play when the general centres are 

 of themselves unable to effect a sufficiently rapid compensation. 



While it must be admitted that our knowledge of the precise locations, 

 physiological peculiarities, and correlations of the thermogenic centres is by no 

 means complete, we have at our disposal some most important and significant 

 data. The general thermogenic centres have been shown by Reichert 1 to be 

 located in the spinal cord. The thermogenic centres in the brain are either 

 thermo-accelerator or thermo-inhibitory. Thermo-accelerator centres probably 

 exist in the caudate nuclei (possibly also in the tuber cinereum and optic 

 thalami), pons, and medulla oblongata. 2 



Excitation of any one of these regions is followed by a pronounced rise of 

 heat-production ; destruction of any one region may or may not be followed 

 by a decrease of heat-production, and if a decrease does occur it may in most 

 cases be attributed to incidental causes, such as shock and other attendant 

 conditions. The centre which is common to the pons and medulla is for the 

 most part probably located in the latter, but it is not so powerful in its influ- 

 ences on thermogenesis as the thermo-accelerator centres in the basal regions 

 of the cerebrum. These cerebral centres are affected by agents which have 

 little or no effect on the heat centres of the spinal cord. Thermo-inhibitory 

 centres have been located in the dog in the region of the sulcus cruciatus and 

 at the junction of the supra-sylvian and post-sylvian fissures. 3 Irritation 

 of either of them is followed by a decrease of heat-production, while their 

 destruction may be followed by a transient increase of heat-production. The 

 cruciate centre is the more powerful. None of these cerebral centres exercises 

 any influence on thermogenesis after section of the spinal cord at its junction 

 with the medulla oblongata. 



Theoretically, these centres are associated in this way : The general thermo- 

 genic centres are in the spinal cord, and while they are perhaps impressionable 

 to impulses coming to them through various sensory nerves, they are not 

 apparently in the least influenced by cutaneous impulses caused by change- in 

 external temperature nor by changes of the temperature of the blood. It is 

 not improbable that these centres are in the anterior cornua of the spinal cord. 

 The thermo-accelerator and thermo-inhibitory centres are connected with the 

 general centres by nerve-fibres, the former influencing the general centres to 

 increased activity, and the latter to diminished activity. The thermo-accel- 



1 University Medical Magazine, 1894, vol. v. p. 406. 



2 Reichert: University Medical Magazine, 1894, vol. 6, p. 303. Ott : Journal of Nervous and 

 Mental Diseases, 1884, vol. 11, ]>. 141; 1887, vol. 14, p. 154; 1888, vol. 15, p. 85 ; Therapeutic 

 Gazette, 1887, p. 592; Fever, Thermotaxia, <ni<l Oalorimetry, 1889. Aronsohn and Sachs: Pfluger's 

 Archiv fur Physiologie, 1885, Bd. 37, S. 232. Girard: Archives de Physiologic normale el patholo- 

 gique, 1886, t. 8, p. 281. Baginsky und Lehmann : Virchovfs Archiv fw Physiologie, 1886, Bd 

 106, 8. 258. White: Journal of Physiology, 1890, vol. 11, p. 1 ; 1891, vol. 12, p. 233. Baculo: 

 Centri temici, 1890, 1891, and 1892. Tangl : Pfiiiger's Archiv fur rinisini„ ; ,ie, 1895, Bd. OS, S. 559. 

 Schultze: Archiv fur experimentelle Pathologic und Pharmakologie, 1890, Bd. 43, S. 193. 



3 Wood: "Fever" Smithsonian Coutrihutions to Knowledge, 1880, No. 357. Ott: Journal of 

 Nervous and Mental Diseases, 1888. 



