MODE OF TERMINATION OF MOTOR NERVES IN AMPHIBIA. 215 



easily hither and thither in the sarcolemma, if care be taken that 

 the lumen of the latter remains open, and all pressure be avoided. 

 The intra-muscular axis cylinders of muscular fibres thus 

 treated dissolve first at the points, then separate along their 

 whole extent from the sarcolemma, and fall towards the centre 

 of the tube, so that on shaking they float to and fro in the fluid. 

 And there is yet another experiment which has led Cohnheim 

 to the same result. He dipped fresh muscular fibres for a short 

 time in acid, treated them with a weak solution of nitrate of 

 silver, washed them with water, and allowed them to blacken 

 in the light. A fine precipitate of silver occurred in the form 

 of thin membranes between the muscle cylinder and the sarco- 

 lemma, which, after exposure to light, surrounded the muscular 

 substance with a black layer beneath the sarcolemma. In this 

 layer, stained with silver, the whole intra-muscular nervous 

 apparatus appears as a white silhouette, indicating that some- 

 thing is here intercalated between the sarcolemma and the con- 

 tractile substance, and this indeed is the intra-muscular axis 

 cylinder. This experiment is interesting on several other 

 accounts ; for, in the first place, previous to the blackening 

 taking place, the form of the nerve termination appears with 

 surprising clearness, because the fine layer, composed of the silver 

 precipitate, surrounds in the first instance everything that is 

 of nervous nature with very distinct limiting lines ; and, 

 secondly, a means is obtained which is unfortunately the only 

 one at present known, by which preparations of muscles ex- 

 hibiting the mode of terminations of the nerves can, for a few 

 months at least, be preserved. Lastly, it shows that there is pre- 

 sent between the sarcolemma and the axis cylinder on the one 

 hand, and between this and the contractile substance on the 

 other, a capillary layer not capable of precipitation with a silver 

 solution under the conditions which the experiment accidentally 

 realizes, a something which is different from that which sur- 

 rounds the whole contractile substance beneath the sarcolemma. 

 The experiment of making the nerves float by treating the 

 muscular tubes with diluted hydrochloric acid renders the for- 

 mer indeed probable ; for it is then seen that the axis cylinder, 

 beginning at the point, only gradually separates from the sar- 

 colemma, to which it appears to be very firmly adherent ; the 



