MUSCLES, NERVES, AND ELECTRICAL ORGANS. 201 



as they had done formerly for his own. Matteucci's hypothesis 

 is undeniably to be preferred, inasmuch as something- may be made 

 of it. It is a good discussable mode of conception, of which I 

 am all the more ready to take account that the fundamental idea 

 is my own. As early as in my researches in 1849 I considered 

 expressly, and tested with all the apparatus which then existed, the 

 possibility of explaining- the extrapolar electrotonic current by the 

 assumption then much in vogue, that the axis cylinder conducted, 

 and the medullary sheath insulated. In that case a branch current 

 would flow from the anode along the perineurium to the next cross 

 section, along the axis cylinder to the section nearest to the anode, 

 and back through the perineurium to the kathode. In this form, 

 however, the hypothesis did not stand the test 1 . 



Whether it would do so in the form which Hermann gave it, 

 on the ground of the inferior transverse conductivity of nerves 

 discovered by him, I rather hesitate to believe on his word, and 

 I have not yet had time to convince myself about it by experi- 

 ments of my own. If I succeed in doing this I shall 'freely 

 acknowledge it. In the meantime it is certain that the intrapolar 

 tract not only possesses the negative polarisation which is rather 

 physical, and on which the extrapolar currents may depend, but 

 also that positive polarisation of a more physiological nature which 

 my hypothesis requires. It is certain that even if the extrapolar 

 electrotonic currents depend merely on diffusion of current, the 

 nature of electrotonus as consisting in positive polarisation is 

 not thereby affected. We should only be rid of the doubtful 

 necessity of explaining its spread beyond the electrodes. It is 

 further certain that while I discovered the positive polarisation of 

 the intrapolar tract at a time when I possessed none of the appa- 

 ratus of the present day, Hermann, who found this apparatus ready, 

 has from 1867 till now overlooked the fact which is fundamental in 

 the field upon which he appeared as a reformer. Finally, it is certain 

 that all that he thought out regarding electrotonus, and which he 

 propounded with so much confidence, is reduced to mere chaff in 

 presence of this fact, and that the investigation of electrotonus 

 in general must begin from this fact. Hermann stated that the 

 comparison of a living nerve and one killed by exposure to steam, 

 showed no apparent difference as a conductor in favour of the 

 former, as must be the case if a current set free electromotive forces 

 in the same direction as itself in the living nerve ; and he regards 



1 Loc. c\t. vol. ii. part i. pp. 229, 275-282, 347-350. 



