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Proceedings of Royal Society of Edinburgh. [sess. 
12.30. — R. sciatic nerve gives feeble twitch of muscles at 90 mm., 
fair contraction at 70 mm. L. sciatic nerve gives no response at 0. 
Muscles are equally excitable on both sides to direct stimulation. 
In another experiment of the same kind 0*1 grm. abolished the 
excitability of the sciatic nerve in eighteen minutes. It is evident 
therefore that very large doses of morphine do paralyse the termina- 
tions of motor nerves, but that ordinarily death ensues before the 
depression is very marked. With small therapeutic doses it is hardly 
possible that even a trace of this action is present. 
On sensory nerves and their terminations morphine, even in large 
doses, has probably a scarcely appreciable effect. The condition of 
affairs is no doubt much the same as with motor nerves, — that is, if 
large doses could be applied directly to the nerve terminations, the mor- 
phine would act as a paralysant to the nerve tissue, but by the ordinary 
methods of administration its effect is practically nil. It is evident 
during the tetanic stage that the sensory nerves are perfectly acute, as 
the slightest stimulation of the skin brings on a spasm. The common 
method of applying opium fomentations as an anodyne has probably 
no action except what results from heat and moisture, as the alka- 
loids cannot penetrate the skin, and even if they did do so, would not 
be in sufficient amount to paralyse the sensory nerve terminations. 
Mammalia . — The higher animals are affected by morphine in the 
same way as frogs, but there are certain differences in the symptoms, 
depending not on a different action of the poison, but on differences 
in the nervous system, and on the closer interdependence of its 
various parts in the higher animals. Frogs live long after the 
respiratory centre is paralysed, whereas mammals die at once, so 
soon as this centre is thrown out of action, hence the longer con- 
tinuance of the symptoms and the marked development of the 
tetanic stage in the former. The greater importance of the spinal 
cord relatively to the brain in batrachians has no doubt also an 
effect in modifying the symptoms. Rabbits, cats, and dogs pass 
through a narcotic and a tetanic stage if the dose be large enough. 
With small doses only the first stage is seen. (For doses and 
particulars, see Tables of Experiments.) 
The condition of affairs is the same as with frogs. Small doses 
depress the brain and spinal cord, while larger ones throw the cord 
into a condition of hyper-excitability. Whether large doses affect 
