INVOLUNTARY MUSCULAK FIBRE 17 
appearance, in both kinds of muscle, allows of the supposition that in both 
it is constructed in a similar way, viz. of small particles or “‘ sarcous elements ”’, 
and that a difference in the arrangement of these elements gives a dotted appear- 
ance to the involuntary, and a tranverse striation to the voluntary fibres. . . . 
On the addition of acetic acid, fusiform or rod-shaped corpuscles make their 
appearance in all muscular tissue; these bodies, which appear to belong to 
the sheath of the fibre, approach nearest in their characters to the corpuscles 
belonging to the yellow or elastic fibres which pervade various other tissues ; 
and from the apparent identity in nature of these corpuscles in the different 
textures in which they are found, and especially in voluntary, as compared 
with involuntary muscle, it is scarcely conceivable that in the latter case 
exclusively they should be the nuclei of oblong cells constituting the proper 
muscular tissue.’ 
Mr. Ellis, then, agrees with Mazonn in believing that the tapering fibre- 
cells of Kolhiker owe their shape to tearing of the tissue ; and he regards the 
nuclei as mere accidental accompaniments of the proper muscular structure, 
probably belonging to the sheath of the fibres, which, according to him, are 
of rounded form and uniform width. 
The distinguished position of Mr. Ellis as an anatomist makes it very 
desirable that his opinion on this important subject should be either con- 
firmed or refuted, and the object of the present paper is to communicate some 
facts which have recently come under my observation, and which, I hope, may 
prove to others as unequivocally as they have done to myself, the truth of 
Kolliker’s view of this question. 
In September last, being engaged in an inquiry into the process of inflam- 
mation in the web of the frog’s foot, I was desirous of ascertaining more pre- 
cisely the structure of the minute vessels, with a view to settling a disputed 
point regarding their contractility. 
Having divided the integument along the dorsal aspect of two contiguous 
toes, I found that the included flap could be readily raised, so as to separate 
the layers of skin of which the web consists, the principal vessels remaining 
attached to the plantar layer. Having raised with a needle as many of the 
vascular branches as possible, I found, on applying the microscope, that they 
included arteries of extreme minuteness, some of them, indeed, of smaller 
calibre than average capillaries. A high magnifying power showed that these 
smallest arteries consisted of an external layer of longitudinally arranged 
cellular fibres in variable quantity, an internal exceedingly delicate membrane, 
and an intermediate circular coat, which generally constituted the chief mass 
of the vessel, but which proved to consist of neither more nor less than a single 
LISTER I C 
