THE PHARMACOLOGICAL ACTION OF TUTU. 



311 



fact that a younger animal was used for this experiment than for the others represented 

 in the figure. The temperature appears to be more easily affected by tutin in young 

 than in adult or old animals. After lethal doses of tutin the temperature in the few 

 cases I have investigated fell from the first, and showed no tendency to recover, notwith- 

 standing the continued convulsions. 



A fall of temperature has been shown by Harnack # and his pupils to occur after 

 the administration of most convulsants. Harnack t was inclined at first to the view 

 that they acted by stimulating the inhibitory mechanism of the heat-regulating centre 

 in the brain, but later, as the result of further investigations with sodium santoninate 

 and santonate.J he came to the conclusion that the antipyretic action of these 



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Fio. 10.— Influence of tutin on temperature of rabbits. I = 0'3 mg. per kg. body-weight ; II = - 5 mg. per kg. body-weight ; 

 III = 1 mg. per kg. body-weight ; IV = 1'5 mg. per kg. body-weight, adininistered hypodermically. 



convulsants is due to loss of heat owing to dilatation of the cutaneous vessels. This 

 dilatation is brought about in all probability by stimulation of the vaso-dilator 

 mechanism in the medulla, He does not think it follows that all convulsants which 

 cause a fall of the body temperature act in this way, but he withdraws his former 

 explanation of their mode of action. More recently Hayashi§ has shown that 

 convulsants temporarily reduce the fever caused by heat-puncture, and in consequence 

 he concludes that the action of these substances is a depressant one on the heat- 

 regulating centre. 



Part of the evidence brought forward by Harnack in support of dilatation of the 



* Archivf. exper. Path. u. PharmaL, xxxviii. p. 397 [1897] ; xl. p. 151 [18971. 

 t Ibid, xxxviii. p. 421 ; xl. p. 152. + Ibid., xlv. p. 272 [1901]. 



TRANS. ROY. SOC. EDIN., VOL. XLVII. PART II. (NO. 13). 



§ Ibid., 1. p. 247 [1903]. 

 47 



