in GREEN AND BROWN FROG 131 



course, the influence on motor nerves prevents the 

 spinal influence from being detected, unless the experi- 

 ment is performed in a particular manner. In jR. 

 temporaries the symptoms are quite different ; tetanic 

 convulsions appear, and if the dose is considerable, 

 motor paralysis ensues later. The case is the same 

 with the common toad. 



Similar facts had been witnessed years before by 

 many physiologists. As early as 1864 my much re- 

 gretted master Vulpian : found that the same poisons 

 operate differently on the circulatory system of the 

 two species. Two years afterwards J. L. Prevost 2 wit- 

 nessed facts confirmatory of the preceding, concerning 

 the same animals when subjected to the influence of 

 veratrin ; the heart being arrested in one case, while 

 it is merely slackened in the other. Then Schmie- 

 deberg, in i8/4, 3 took up the question, studying the 

 influence of caffein, and saw that in R. temporaria 

 caffein operates in determining a local action which 

 gradually spreads a sort of muscular rigor, accom- 

 panied by a decrease in excitability ; in R. esculenta 



1 Sur les Differences entre les Grenouilles rousses et les Grenouilles 

 vertes sous le Rapport des Effets produits par les Substances Toxiques et 

 sptcialement par les Poisons du cceur. Bull. Soc. Philomatique, 1864, 

 p. 94. 



2 J. L. Prevost, Recherches Experimentales relatives a F Action de 

 la Veratrine. Thesis, Paris, 1886. 



3 Ueber die Verschiedenheit der Caffeinwirkung an Rana temporaria 

 und R. esculenta. Arch. f. Exp. Path, und Pharm. 1874. 



K 2 



