CRITIQUE OF THE EYE-MUSCLE NERVES. 233 



relation they can be followed to the insertion of the muscle 

 upon the eye-ball. 



The nerve for the m. rectus inferior after separation 

 from the nerve last described descends at once to the dor- 

 sal surface of its muscle and here breaks up into 

 numerous branches. Of these those with coarse fibres 

 enter the belly of the muscle, while the fine fibres run to 

 the small fibred ventral edge of the muscle, which they 

 follow to the insertion upon the eye -ball. 



V. — Critique of the Eye-Muscle Nerves. 



In the case of each of the six eye-muscles of which we 

 have just been treating, the side along which the finer 

 fibres of its nerve ran contains much smaller muscle 

 fibres than those which make up the body of the muscle, 

 the diameter of these small muscle fibres often being no 

 greater than that of a large nerve fibre. The smaller 

 muscle fibres are not merely the ends of larger ones which 

 have become attenuated near their insertion, but they run 

 for nearly the whole length of the muscle, maintaining the 

 same diameter and the same relation to the larger ones. 

 They do not appear to differ from the ordinary fibres 

 except in size, in their constant relation to the finer nerve 

 fibres and particularly in the fact that they are in places 

 more closely enveloped by a dense and very rich plexus 

 of these finer nerve fibres and by a nucleated connective 

 tissue interstitial substance. The investigation of the 

 nerve endings here by proper methods might yield inter- 

 esting results. 



That the small muscle fibres and the small nerve fibres 

 are related can scarcely be doubted. The source of the 

 small nerve fibres could not be certainly determined. 

 The most natural supposition is that they come from the 



