TERMINATION OF MOTOR NERVES IN VERTEBRATA. 231 



Krause, in preparations where the nerves had undergone much stretch- 

 ing, and had on that account become attenuated, mistook the point of 

 attachment of the nerve which had thus been rendered conical with 

 the ultimate nuclei of the sheath of Schwann for the nerve eminence ; 

 whilst Rouget obviously overlooked the entire expansion of the now 

 no longer medullated nerve, after he had been accustomed to the in- 

 finitely more sharply denned images of the same parts in the muscles 

 of lizards. In the meanwhile Engelmann (38) had been successful in 

 discovering the elongated expansion of the axis cylinder in the frog, 

 with the exception only that he denied the minute anatomy of the 

 terminal bulbs, and believed a granular substratum to be here present, 

 constituting an intermediate structure between nervous and contractile 

 tissue, and continuous with both. The objections to this view, extended 

 by Engelmann to the muscles of all animals, have been already ad- 

 duced, and it need here only be added that his description of the 

 granular mass in the frog is decidedly erroneous. The most satisfac- 

 tory demonstration of the accuracy of the mode of termination of the 

 nerves described in the text results from the application of the silver 

 mode of preparation, and has been furnished by Cohnheim (46, 60) ; 

 this mode is equally well adapted to display the terminal nerve plate 

 in the Doyerian eminence which comes into view in muscles blackened 

 with silver, in the form of a beautiful white pattern. The same author 

 has pointed out that the isolation of the nerves from the remains of 

 the nerve eminence adherent to them, accomplished by Krause with the 

 aid of moderately strong hydrochloric acid, is not to be regarded as a 

 proof of the eminence being situated on the outer surface of the sar- 

 colemma, because the acid under the conditions maintained by Krause, 

 to wit, degree of concentration and duration of action, effects the solu- 

 tion of the sarcolemma, and consequently lays bare the muscle, and 

 breaks down the continuity of the nerve with the muscular fibre. The 

 existence of the terminal plate has still more recently been vigorously 

 contested by Rouget (56) and Krause, who explain the whole appear- 

 ance as a hitherto undescribed post-mortem phenomenon of coagula- 

 tion, in contradiction to which, again, Rouget stated that the true 

 termination of the axis cylinder in the nerve eminence consists in its 

 metamorphosis into a granular mass with interspersed nuclei. Rouget 

 soon again retracted this view for the muscles of Arthropoda, and 

 especially for those of Crustacea, in which he discovered an analogue 

 to the plate, or at least to the more fibrous mode of the termination of 

 nerve fibres that occurs in the frog. It is reserved for further research 

 to decide whether Rouget' s statements are correct, to the effect that 



