THEIR NATURE AND EFFECTS.
was ligatured and the other was poisoned, when the cord was excited by a current the stimulus had to he transmitted to the non-poisoned leg through the trunk of the nerve which was unaffected, whereas on the gther leg it had to overcome the resistance induced by the paralysing poison. There is no need to suppose a special effect of the poison on the ends of the motor nerves; the different lengths of the trunks affected would account for a considerable difference. To this we have also to add the paralysing effect on muscle, which, though not so great as on the nerve, is yet not unimportant, and would tell on the same side.
Moreover, it does not necessarily follow that because a nerve to which poison has had access conveys electrical stimuli in a very imperfect manner, or not at all, therefore that the effect of that poison has been to paralyse the nerve. It is unfortunate that the only test we have of the vitality of a nerve is its power of causing contraction in a muscle when irritated by electricity or mechanically. It would be going too far to say, therefore, that because a nerve did not transmit such rude stimuli it was dead; and even if the animal loses the power of withdrawing a limb that is being painfully stimulated, the break in the power of conducting impressions or stimuli may be in any part of the nervous chain necessarily called into requisition in such an action.
A poison that produces death by totally different
