NATURAL SCIENCES OP PHILADELPHIA. 375 



galvanic current to produce reflex movements. 2.10, the strongest 

 current no longer causes reflex movements, but the animal con- 

 tinues to breathe until 2.19. 



This experiment, when taken in connection with thirteen others 

 which yielded similar results, proves that early in conia-poison- 

 ing there exists no increased excitability of the cord, as is claimed 

 by Casaubow (loc. cit.), Pelvette and Damourette (loc. cit.), for if 

 there had been, the acetic acid would have produced reflex move- 

 ments more rapidly, instead of more slowly, after injecting the 

 conia, and it would have taken a much weaker, instead of a much 

 stronger current to produce reflex movements. These experi- 

 ments also render it probable that the action on the cord is one 

 of depression, but this is uncertain, as the later symptoms of de- 

 pression might be caused by the paralysis of the terminal extrem- 

 ities of the efferent nerves. To obviate this source of error, all 

 the bloodvessels of a frog's leg were tied and the experiments re- 

 peated. 



Exp. 21. On a large frog. Tied all the bloodvessels of the left 

 posterior extremity, carefully excluding the nerves ; the weakest 

 current that would cause reflex movements in the injured limb 

 was then determined. 3.58, injected one-eighth drop of conia. 3.59, 

 acetic acid applied causes no reflex movements (previous to the 

 injection it caused movements in one second). 4.01, it takes the 

 strongest current to produce reflex movements in the ligatured 

 limb. 



Exp. 22. Tied all the bloodvessels of the left posterior extrem- 

 ity of a large frog, and then determined the weakest current 

 which would cause reflex movements in the injured limb. 4.15, 

 injected one-eighth drop of conia. 4.16^, a much stronger current 

 is required to produce reflex movements in the ligatured limb. 

 4.20, the strongest current applied to the ligatured limb will not 

 cause reflex movements, though respiration continues and galvan- 

 ization of the spinal cord causes movements in the ligatured 

 limb. 



As the ligatured limb, in the last-mentioned experiments, 

 failed to respond to irritants after the access of the drug to the 

 trunks and periphery of the nerves was prevented, this failure 

 must have been due to paresis of the spinal marrow, and not to 

 paralysis of either the afferent or efferent nerve-fibres. It is there- 

 fore proven, that, instead of there being a stage of spinal excite- 



