66 CUBEENT FORCE CHAP. VI. §. I. 



as it takes place in the muscular tissue, is so rapid a 

 change as may occur in some of the secreting organs, 

 that the tissue is deposited and immediately taken 

 up again, or constantly undergoing changes; I am 

 far from supposing this, and do not pretend to be 

 able to trace out the exact changes that take place, 

 nor the time that is required to effect these changes. 

 We have, however, under any point of view, to 

 consider how this electric condition of the tissue is 

 brought about, and what other circumstance, I may 

 ask, is more likely than nutrition ? We have a vera 

 causa at work, and such a one as is likely to produce 

 the very result observed. I may also refer to the 

 results obtained by Matteucci, in which he has shewn 

 the dependence of the current (muscular) upon the 

 state of the tissue in regard to its nutrition, that what- 

 ever influences the latter affects the former. At the 

 same time, I am perfectly aware that objections may 

 be raised to his mode of conducting the experiments, 

 viz. by forming piles of animal substances, but 

 I cannot help thinking that these objections may be 

 carried too far. 



It may be asked, and with some justice, how can 

 we account for the external surface of the muscle 

 being positive to the divided transverse surface ? we 

 can understand, it may be said, the cation existing 

 in the blood producing its positive state, but where is 

 the cation in the external surface ? 



I shall allude to this question in a future chapter, 

 when it will again come under consideration ; and as 



