PHYSIOLOGICAL ACTION, AND ANTAGONISM. 
213 
Comparison between the Action of Ammonia and the Compound Ammonias. 
Ammonia itself lias a convulsant action, the convulsions apparently being due to its 
effect upon the spinal cord, like those of strychnia. It differs, however, from strychnia 
in this respect, that the convulsions do not continue long, apparently because the 
motor nerves soon become exhausted, so that the excited spinal cord can no longer 
induce muscular contractions. The only one of the compound ammonias, in which 
one atom of hydrogen only is replaced by an alcohol radical, that we have experi¬ 
mented with is ethylamine; and this we find has also a convulsive action, probably 
the same in nature as that of ammonia. It has but a feeble paralyzing action on 
motor nerves. But this is only true of a single stimulus or of a few stimuli. 
'When the nerve is subjected to rapidly repeated stimulation, it becomes very quickly 
exhausted. Ethylamine, therefore, while not directly paralyzing the excitability 
of the nerve, greatly lessens its endurance and power of work. It will thus have a 
similar effect to ammonia in shortening the convulsions, and thus rendering them 
like those of ammonia, and unlike those of strychnia. Its action on muscle itself 
appears to be very similar to that of ammonia. First it increases the excitability 
of the muscle, but afterwards diminishes it, and renders the curve both lower and 
longer. 
Trimethylamine was found by Husemann to have a tetanising action even on Frogs, 
like that of ammonia. In our experiments, however, we found gradual failure of the 
circulation and of reflex without any spasm. This difference between his results and 
ours may be possibly due either to our having employed different kinds of Frogs or 
to our having experimented at different seasons and under different temperatures. 
Another possibility is, that the Frogs he employed were stronger, and that their 
circulation was more vigorous than ours : for we have already noted that ammonium 
bromide produced tetanus in Frogs, but this came on at a late period in the poison¬ 
ing, and unless the Frog was strong, and the circulation vigorous, the animal died 
before the tetanus made its appearance. 
With triethylamine we noticed a great failure of reflex, unaccompanied by spasm; 
with both triethylamine and trimethylamine the action appeared to be slower than 
that of ethylamine. In one case of poisoning by the latter, tonic spasm occurred in 
70 m after injection, whilst in two hours after the injection of a larger quantity of 
triethylamine and trimethylamine, a faint reflex action was still present, and the 
circulation was maintained. The action of trimethylamine and triethylamine on 
motor nerves and muscle is very much the same as that of ethylamine or ammonia. 
From a comparison of ammonia with these compound ammonias it appears that the 
replacement of hydrogen by alcohol radicals tends to diminish the convulsant action 
of ammonia itself, and that the diminution is greater in proportion to the number of 
hydrogen atoms substituted. 
We have not obtained any distinct evidence that the substitution of alcohol 
