446 



Dr. W. Kiihne. On the 



expends its action upon this exclusively; that which follows on as 

 muscular activity is the nerve's work no longer. 



Galvani and his successors for more than a century suspected that 

 nervous forces were electrical, and, in reality, the celebrated champion 

 of electro-physiology in our day has been able with the galvanometer to 

 render the excitation of nerves, unattached to muscles or ganglion- 

 cells, evident as the negative variation of the natural nerve -current, to 

 cause movement of a magnetic needle instead of a muscle, or to put 

 the needle in the place of sensation. After this no consideration of 

 the nature of nervous activity is conceivable which does not take 

 into consideration this discovery of du Bois-Reymond's — least of all 

 where the nerve has to excite something with which it is not 

 fused, like muscle, but which it only touches, and that not directly, 

 while still invested by the axolemma. Only during excitation, as 

 Ludimar Hermann has taught us, are electric currents issuing from 

 the nerve through its conducting surroundings, in which the course 

 of these currents of action is to be estimated from the duration of the 

 negativity of the nerve-tract excited, and from the speed of propaga- 

 tion of the nerve-wave, if we know the conductor and the disposition 

 of the nerve. The motor ending fixes the latter, and so peculiarly 

 that we can only presuppose from it a furthering of the excitor effects 

 of the currents of action. 



The currents of action of muscle, whose electromotive behaviour 

 agrees so wonderfully with that of nerve, have long been proved to 

 produce excitor effects, although only powerful enough to act upon 

 nerves ; but there are also, under certain conditions discovered by 

 Hering, such effects from nerve to nerve (25). Is the possibility, we 

 may hence ask, to be excluded of one muscle exciting another, and is it 

 quite impossible that a nerve only throws a muscle into contraction by 

 means of its currents of action ? 



The first question we can answer. I will do so by a simple experi- 

 ment. Two muscles, the nerves of which are disposed of by poisoning 

 with curare, need only to be pressed together transversely over a narrow 

 area to make a single muscle of them of double length, in which 

 the stimulation and contraction are propagated from one end to the 

 other. Since the transference from one muscle to the other is done 

 away with as soon as we bring the finest gutta-percha between the 

 muscles as an insulator, or gold-leaf as a secondary circuit, the first 

 muscle must have excited the second electrically (26). 



NOTES. 



1. The most complete exposition of these important later discoveries on the 

 reproduction of the cell is to be found in the book of W. Flemming, ' Zellsub- 

 stanz, Kern und Zelltheilung,' Leipzig, 1882. Cf. the " Kurze historische Ubersicht " 

 (p. 385), with the quotations from the works of Schneider. Strassburger, Butschli, 



