NATURAL SCIENCES OF PHILADELPHIA. 373 



convulsions of cbnia-poisoning are cerebral, and not spinal, as 

 Christison supposed. 



These convulsions, according- to Yan Praag (loc. cit.), are 

 always tonic in birds and fishes, but they may be either clonic or 

 tonic in mammals ; they never occur in the batrachian, except 

 when the drug is directly applied to the brain, when they invaria- 

 bl} r are present. 



Action on the Spinal Cord. On this subject the conclusions, 

 or, more correct^, suppositions, of different investigators are ab 

 variance. Christison (loc. cit.), Van Praag (loc. cit.), and Verigo 

 (Schmidt's Jahrbiicher, Bel. cxlix. S. 16) say that it acts forcibly 

 as a depressant. Yerigo is most positive in his declaration that 

 all the symptoms of conia-poisoning, except paralysis, may be 

 attributed to its depressing action on the cord. Casaubow 

 (Practitioner, 1869) nnd Pelvette and Martin Damourette (loc. 

 cit.) have come to a directly opposite conclusion, they believing 

 that the drug is a spinal excitant. Pelvette and Damourette write: 

 " Its excitability is but little influenced by feeble poisonous doses, 

 since these do not produce convulsions at first, since the voluntary 

 and reflex movements persist until the end in the frog, and since 

 cold-blooded animals succumb without any marked change of the 

 intellectual or instructive faculties." . . . . " With strong doses 

 there exists an undoubted increase of excitability of the nervous 

 centres, which is evidenced by tetanic movements and convulsive 

 tremblings, and marked a little later by paralysis of the motor 

 extremities. All our experiments place beyond doubt this exalta- 

 tion of the spinal motor centres." 



There are several points in this statement with which the writer 

 must disagree: first, they say " the voluntary and reflex move- 

 ments persist until the end in the frog, where feeble poisonous 

 doses are given." The writer has given conia to more than a 

 hundred frogs, thirteen of whom recovered, and, except where the 

 principal artery of a limb was tied, in all of them complete aboli- 

 tion of voluntary and reflex movements occurred at some period 

 of the poisoning. The two following are illustrative experi- 

 ments : 



Exp. 18. On a medium-sized frog. 7.43, injected ^ v of a drop 

 into the abdomen. 7.43f , neither voluntary nor reflex movements 

 can be excited by the strongest current applied to the sciatic 

 nerve. 



