1862.] 73 



in which the pale nerve-fibres terminate. Thus in many cases there 

 is an appearance on the pale fibres of numerous short, pointed or 

 blunt, lateral processes, or at least a certain want of definition in their 

 outline, indicating that they may possibly send out still finer offsets. 

 At the same time I have not been able to trace the matter further in 

 this direction ; and as regards the few undoubted cases of conjunction 

 of the pale fibres which I have hitherto met with, I am not disposed 

 to interpret them in the above sense. Moreover we can often see 

 the pale fibres so sharply and beautifully defined, and maintaining so 

 long their rectilinear course, that it is difficult not to regard them as 

 the true terminations ; so that the above-mentioned appearances to 

 the contrary may perhaps be owing to the effect of the reagents used, 

 which, while they clear up the muscular fibres, may attack more or 

 less the extremely delicate substance of the pale nerve-fibres. 



On the Distribution of Sentient Nerves in the Muscles of the Frog. 



Having thus laid before the Society the results of my observations 

 on the motorial nerves of the frog's muscles, I have now to speak 

 of the terminations of other nerves which are distributed to the 

 muscles of the same animal, and which are probably sensory in their 

 office. Nerves which are probably of a sentient nature have 

 already been observed in human muscles by myself, and in the 

 cutaneous pectoral muscle of the frog by Reichert, who takes the 

 same view as to their nature. As, however, the mode of termination 

 of these nerves has not heretofore been fully investigated, I have 

 been led to extend my inquiries to that question, and beg leave now 

 to state the principal results. 



The sentient nerves of the cutaneous pectoral muscle of the frog 

 are supplied by the common moto-sensory nerve of the muscle 

 (fig. 2, a a ), from which they come off at different points as 

 single fibres, and, proceeding to the muscle, branch out upon it in its 

 whole extent, even in parts which are destitute of motorial nerves. 

 As regards the details of distribution, however, there is not even an 

 approach to uniformity in any two muscles, and therefore, instead 

 of attempting a general description, I will refer to fig. 2, which 

 represents an individual case as seen under a low magnifying power, 

 carefully copied from nature. 



In this instance the sentient nerves consisted of five principal 



