341 



in a of Fig. 2; that they, like the endiugs above referred to, are in 

 the connective tissue, this figure may serve to show. 



That the nerve -endings here described are sensory, is further 

 suggested by the fact, that in this investigation no other forms of 

 sensory endings have been found in the extrinsic eye- muscles of the 

 rabbit. That special sensory endings, having a wide distribution, are 

 found in striated muscles aud their tendinous prolongations, numerous 

 observations have shown, and that the sensory nerve fibres terminating 

 in them may readily be stained in methylene blue has also been de- 

 monstrated (see Huber-De Witt, loc. cit.) 



Marchi *) has shown that sensory end-organs are to be found in 

 the tendons of the eye-muscles of a number of mammals. That sen- 

 sory endings in the tendons of the recti muscles of the orbit of the 

 dog and cat are readily stained in methylene blue, I have frequently 

 observed in an investigation on the structure of the sensory endings 

 in the extrinsic eye-muscles. In the extrinsic eye-muscles of the rabbit, 

 no sensory endings in the tendon have been observed. 



To summarize briefly -- the "atypical motor endings" described 

 by Retzius as found in the eye-muscles of the rabbit are looked upon 

 as sensory endings for the following reasons: — 



1. Typical motor endings are found in these muscles. 



2. The sensory nerves terminate nearer the tendinous insertion 

 of the muscle fibres. 



3. The sensory nerves in the eye -muscles resemble in structure 

 the terminal branches of medullated nerves terminating in known sense- 

 organs. They present short internodal segments; are surrounded by 

 a nucleated fibrous sheath, which although not well defined may be 

 regarded as a sheath of Henle. 



4. The termination of the sensory fibres, both of the side branches 

 and terminal branches is in the connective tissue, outside of the sarco- 

 lemma, breing often, however, in very close relation to the muscle fibres. 

 No distinct Doyere's elevation is noticed at the place where such an 

 ending seems to terminate on the muscle fibre, and there is no 

 perceptible increase of muscle nuclei in the neighborhood of such an 

 ending. 



5. More than one sensory ending is found on one and the same 



1) Marchi, Ueber die Terminalorgane der Nerven (Golgi's Nerven- 

 kürperchen) in den Sehnen der Augenmuskeln. A. v. Grakfe's Arch. f. 

 Ophthalm., Bd. 28, 1892. 



Anat. Anz. XV. Aufsätze. 23 



