58 



The convulsing poisons do not appear to excite the muscles 

 or any part of the nervous system, and consequently they do not 

 act directly. They act merely in increasing the vital powers of 

 the nervous system, so that a slight excitation of the skin or ano- 

 ther part where there exist nerves of sensation is sufficient to pro- 

 duce convulsions. Therefore these poisons act indirectly in the pro- 

 duction of convulsions. They do not produce convulsions, they 

 merely act upon the nervous system, so as to render it capable of 

 producing convulsions when it receives an excitation. They do 

 not excite the nervous system, and their mode of action is altoge- 

 ther different from that of the mechanical, physical, and chemical 

 excitations which directly produce convulsions, when they are 

 applied to the medulla oblongata, or to the spinal cord. 



This mode of action was already known as regards strych- 

 nine. Long ago Mr. Magendie* found that animals poisoned 

 by nux vomica, frequently remain without convulsions as long as 

 they are left without excitation, but that fits are immediately 

 produced when they are touched. Since that time Stannius,j- 

 Van Deen,{ Pickford,|| J. W. Arnold, Meyer, of Zurich,!! Mar- 

 shall Hall,** and A. Barnard, ff have observed many facts 

 proving that strychnine does not directly produce convulsions. 

 The following experiment, which I performed with the assistance 

 of Dr. Bonnefin, is still more demonstrative. 



I introduce a large dose of strychnine into the stomach of a frog, 

 after the removal of its brain and of its medulla oblongata. As 

 the voluntary and the respiratory movements are then impossi- 

 ble, there is no spontaneous movement at all, and if the animal 

 is left perfectly quiet there are no convulsions. But as soon as 

 it is excited, even by the slightest touch, tetanus occurs. 



In this case, it is evident that the convulsive fit is merely a re- 



* Rxamen de I'action de quelques vegetaux sur la Moelle epiniere. Paris 

 1809, p. 7. 



t Mueller's Archiv. 1837, p. 223. 



jTraites et deeouvertes sur la Moelle epiniere, 1841. p. 123, 

 || In Rorer und lT rar( |erlich'8 Vieiteljaheschrift. Bil. 2. 1843 ; p. 430. 

 Ueberdie verrichtunsj der VVerzeln der Ruckenmarksnerven, 1844. 

 T Schmidt's Jahrbuc-her, 1847, No. 8. 



** Comptes rendusde 1'Acad. des Sciences, 1847, vol.24, p. 1054. 

 ff Proces verbaux de la Societe Philoinatique, 1847 ; p. 71. 



