Electrical Phenomena accompanying Muscular Contraction. 389 



thought it expedient to contract and tetanize the gastrocnemius 

 before closing the circuit of the galvanometer ; the deviation thus 

 obtained is feebler than that which is due to the current of a muscle 

 in repose, but never in a contrary direction to that due to this 

 current. 



I have already remarked* that this result accords with that 

 which is obtained by the ordinary experiment, in which the muscular 

 current is in circulation previously to the contraction of the muscle. 

 In fact, we know that by continuing to keep the muscle in contrac- 

 tion, above all when the muscle remains tetanized, the electric phe- 

 nomenon accompanying contraction (the effect of which is to pro- 

 duce a deviation of the needle in a contrary direction to that of the 

 current of a relaxed muscle) becomes gradually less intense as the 

 contractions are more and more feeble. 



The method employed by Dr. Radcliffe is the same as that which I 

 followed in my latest experiments ; .that is, he made use of amalgam- 

 ized plates of pure zinc as electrodes, immersed in a neutral solution 

 of sulphate of zinc, and after having ascertained that there was no- 

 thing to fear from the effects of secondary polarity, he says that he 

 finds that the needle deviated by the muscular current descends, 

 during contraction, towards zero, but only more slowly than it would 

 have done had the circuit been opened. 



Dr. Radcliffe next examines another of my experiments, in which, 

 instead of placing a gastrocnemius in the circuit, I employ a thigh 

 cut transversely at the upper extremity, so that the needle remains 

 deviated in a contrary direction to that of the gastrocnemius. In 

 this arrangement of the experiment, when contraction is produced, 

 the deviation of the needle increases, which is perfectly in accordance 

 with the idea that during contraction a muscular current is developed 

 in a contrary direction to the current of the relaxed gastrocnemius. 

 Dr. Radcliffe attempts to explain this result by supposing (if I 

 rightly understand his idea) that during contraction the contacts 

 with the electrodes are deranged so as to facilitate the passage of the 

 current of the relaxed muscle. 



Being unwilling to remain in doubt as to the nature of the elec- 

 trical phenomena of muscular contraction, I have of late repeated 

 and varied my experiments. 



As to Dr. Radcliffe' s first remark, I shall only observe that in 

 the principal experiment the needle does not merely move slowly 

 towards zero during contraction, but is seen, during the first con- 

 tractions, especially when the frog operated on is vivacious, to move 

 rapidly down to zero, to oscillate, to pass to the opposite side, and 

 sometimes even to remain fixed, while thus deviated, for a very short 

 interval of time. This result, which is easily obtained and can be 

 verified without difficulty, is the same, whether the electrodes are 

 of platinum, like those employed by M. du Bois-Reymond, or of 

 zinc. 



It is easy to understand that, in order to succeed in these experi- 

 ments, it is desirable that the needle should be as little deviated as 

 * Nuovo Cimento, September 1858, p. 238. 



