1862.] 77 



the motor nerves. As already noticed, however, they become 

 smaller in size ; indeed the extreme prolongations are in some places 

 attenuated to the size of filaments of connective tissue. Their fine 

 terminations, moreover, lie quite superficially in the perimysium or 

 sheath of the muscle, and between it and the muscular fibres, and 

 are in a great measure confined to the outer or cutaneous surface ot 

 the muscle, although here and there fibres are seen turning to the 

 under surface. 



Nerves of the Blood-Vessels. 



Besides the sentient nerves which I have here described, I have 

 found, in the same cutaneous muscle of the frog, nervous filaments on 

 the blood-vessels, although I have not yet been able fully to satisfy 

 myself as to their source and distribution. These vascular nerves 

 entirely agree in character with the pale sentient fibres, and, like them, 

 are furnished with nuclei. I have found them chiefly on small veins, 

 and on fine vessels on the arterial side of the capillaries, which were, 

 however, destitute of a muscular coat. On these vessels I have traced 

 them a considerable way, passing from one branch to another and 

 often dividing, but have not been able to observe distinct terminations. 

 Now and then also I have recognized them on vessels possessing a 

 decidedly arterial structure; but I am unable to state anything 

 positive as to their arrangement in this case, inasmuch as the nuclei 

 in the outer coat of the small arteries occasion much difficulty in fol- 

 lowing out pale nucleiferous fibres. Once only I was fortunate enough 

 to trace the origin of one of these vascular fibres from a dark-bordered 

 sentient fibre ; and this observation, so far as it goes, together with 

 their distribution to vessels destitute of a muscular coat, favours the 

 notion that the nerve-fibres in question are of the sentient kind. 



On the Nerve-tufts in the Cutaneous Muscle of the Frog. 



In the same muscle of the frog to which I have already made so 

 constant reference, there may be observed, and most commonly about 

 the end of the winter season, from three to five objects of peculiar 

 structure, which at first sight appear to be of the nature of tactile 

 corpuscles or terminal nerve-bulbs, but which really do not belong 

 to that class of organs. The objects in question are indicated in 



