KATHODIC POLARISATION OF MUSCLE. 335 



those symptoms, which, as already mentioned, characterise the 

 proper stage of the action of the poison. Those which chiefly 

 claim attention are more or less marked tetanic stretching spasms 

 of the lower extremities, which succeed each other at rather short 

 intervals, and are ushered in by violent restlessness of the animal 

 and by spasmodic opening of the mouth frequently repeated. It must 

 be considered the rule, to kill the animal before reflex movements 

 are completely extinguished, and at a time when the heart still beats 

 strongly and the circulation is in action throughout the body. The 

 exposed muscles ought to be transparent and to show a good red 

 colour. Another certain criterion of the fit state is, that the muscles 

 of the belly pass into a state of long continuing tetanic contraction 

 on mechanical excitation, such as nipping with the forceps. The 

 same thing should also happen on dividing the nerve in preparing 

 the sartorius. In doing this, it is often seen that after a short 

 pause a more slowly increasing contraction succeeds the rapid 

 twitching at the instant of the section of the nerve; this per- 

 sists for some time and only gives way quite gradually to renewed 

 relaxation. If the frog has been killed at a time when voluntary 

 movements have already ceased and reflex excitability is almost 

 entirely extinguished, then as a rule the muscles are scarcely in a 

 fit condition ; they still react indeed with a tetanic contraction on 

 excitation, but this has not the same long duration, as in an earlier 

 stage of poisoning. 



Certain effects of poison on striated muscles, e. g. the results of 

 treating with solutions of potash or soda salts, can, as is we'll 

 known, be almost removed by washing with an indifferent liquid. 

 Now it is remarkable that this is not the case for veratrine, or at 

 least not nearly to the same extent, whether it is introduced into 

 the course of the blood or is applied directly to the muscle. This 

 circumstance is of importance, because it is thus possible to repeat 

 the experiments of excitation several times in succession on the same 

 preparation, but for reasons to be discussed later, this can only be 

 done between long intervals of rest, during which the preparation 

 remains plunged in a solution of Na Cl, or must at least be kept 

 moist with it. 



If we record the change of form of the sartorius poisoned in the 

 way described with veratrine, which may be effected by securing the 

 ends of bone to which it is attached, either in the usual manner or 

 by means of Bering's double myograph without the middle clamp, 

 one of the two movable non-polarisable electrodes being fixed, curves 



