THE INJURY CURRENT OF NERVE 
22 3 
The arrangement is here seen in its true light as an asymmetrical one, and as 
necessarily productive of an electrical current, and the discovery of such a current in the 
experiment is, therefore, a circumstance capable of anticipation. The application of 
such a test to this idea is, therefore, without point, and in its result a confirmation 
and not a contradiction of the hypothesis. 
After reviewing the evidence whkh influenced Hermann in rejecting Grunhagen's 
theory, including the two points just dealt with, and also the results of the fall 
rheotome experiments previously considered, we may pass to consider Hermann's 
position in 1898/ 
We find the sufficiency of the ' alteration ' theory unabandoned. 2 This is but 
natural. But we find Hermann very seriously considering the claims of a pre- 
existence theory based upon the assumption of two heterogeneous physical structures 
in the nerve fibre. 
We find, in fact, Hermann coming forward with proof of the existence of such 
a difference between the sheath and contents of the nerve fibre, as would, if con- 
clusive, fully justify an a priori plea for the formation of such a theory. And the 
theory which Hermann thus revives is not Grunhagen's, but is Du Bois 
Reymond's tentative hypothesis. 
It is necessary, therefore, to turn again to Du Bois Reymond's crucial test as 
criticized both in 1879 and in 1898 by Hermann ; in fact, as necessarily unfavourably 
criticized by him 1867, for the complete refutation of this supposition could alone have 
prepared the way for the promulgation of the alteration theory. 
Du Bois Reymond thought that he was arranging symmetrically the muscle 
fibre contents and sheath, and paid no attention to the ' nutritive solution ' bathing 
these structures, for he regarded it merely as a neutral conducting medium, and did 
not know that it might play an active part in the production of the phenomenon. 
Hermann saw 5 and sees 4 that the arrangement is asymmetrical, and that 
Du Bois Reymond's test is unconvincing, but he does not see the asymmetry as 
given above, but in the light of the vital states postulated by the ' alteration theory' 
First Fibre 
Sarcolemma. Normal contents. Sarcolemma. 
Second Fibre 
Dying contents. Normal contents. Sarcolemma. 
[. Hermann, PJiuger's Archil'., LXX, p. 523. 1898. The experiments related by Hermann in this paper and in 
another {PJluger, LXVII, p. 240) are of a somewhat remarkable kind. The passage of the strong currents through micro- 
scopical fragments of nerve are observed to produce protrusions of the myelin from the nerve fibre. Upon this bodily 
movement of tube contents upon the tube, arguments are based which lead Hermann to consider the essential physical 
difference between these structures. 
2. Hermann, loc. cit. ; also PJiuger's Archii\, LXXI, p. 296 et sey., 1898. 
3. Hermann, Handbuch, loc. cit. 4. Hermann, PJiuger's Archiv., LXX, loc, cit. 
