1883.] Chemical Constitution, Physiological Action, SfC. 325 



ammonium and of dimethyl ammonium ; trimethyl ammonium and 

 tetramethyl ammonium iodide; ethyl ammonium chloride, diethyl 

 ammonium chloride, iodide, and sulphate; triethyl ammonium chloride, 

 iodide, and sulphate; tetraethyl ammonium iodide. 



The compound ammonias affect the spinal cord, motor nerves, and 

 muscles. The spinal cord is first stimulated and then paralysed, 

 stimulation being evidenced by twitchings or convulsions, and the 

 paralysis by loss of reflex action and motor power. 



There is a marked difference in the action between ammonia 

 and the compound ammonias ; while ammonia causes well marked 

 tetanus, compound ammonias, as a rule, produce symptoms of motor 

 paralysis with the exception of those in which one atom of hydrogen 

 only is substituted by an alcohol radical. This paralysis appears to 

 be partly due to their action on the spinal cord and nerve centres, 

 and partly to a curara-like action on the motor nerves. 



Some of them apparently increase somewhat the excitability of the 

 spinal cord at first, but this is temporary, and is shown rather by 

 hyperesthesia or tremor than by convulsion; and tetramethyl and 

 ethyl ammonium salts differ from the di- or tri-methyl or ethyl 

 ammonias in having a much greater tendency to cause convulsions. 



The effect of the acid radical on the physiological action is less 

 marked in the case of the compound ammonias than in the salts of 

 ammonia itself. 



The iodides of the compound ammonias paralyse motor nerves more 

 quickly than either chlorides or sulphates. 



No difference was observed between the paralysing action of corre- 

 sponding chlorides and sulphates. 



The irritability of the muscle is increased as a rule by the chlorides, 

 sometimes increased and sometimes diminished by the sulphates, and, 

 as a rule, though with some exceptions, decreased by the iodides. 

 The contractile power of the muscle is less affected by the chlorides, 

 more by the sulphates, and most by the iodides. 



On comparing the effect of the substitution of different alcohol 

 radicals for hydrogen in the compound ammonias, it was found that 

 the least active substances were the ethyl, diethyl, and triethyl com- 

 pounds. In the case of the iodides and sulphates of these compounds 

 only, was the minimal irritability of the muscle undiminished. The 

 difference between ethyl and methyl compounds was more observable 

 in the case of the iodides and sulphates than in that of the chlorides. 

 The iodides all have a strong tendency to paralyse the motor nerves, 

 but this is most marked in the case of tetramethyl and tetraethyl 

 ammonium iodides. Tetramethyl appears to act in a somewhat smaller 

 dose than the tetraethyl ammonium. 



Sulphates of the methyl compounds have a stronger tendency to 

 paralyse motor nerves than those of ethyl compounds, and the ethyl 



