550 MR LISTER ON THE MINUTE STRUCTURE OF 
scopical Journal, in which I gave an account of the involuntary muscular fibre 
contained in that organ in man and some of the lower animals, stating that the 
appearances I had met with corresponded exactly with Koiiixrr’s descriptions, 
and illustrating my remarks with careful sketches of several fibre-cells from the 
human iris, isolated by tearing a portion of the sphincter pupillee with needles in 
a drop of water. In 1853, another paper by myself appeared in the same Jour- 
nal, ‘ On the Contractile Tissue of the Skin,” confirming KoLiikEr’s recent dis- 
covery of the “arrectores pili,’ and describing the distribution of those little 
bundles of unstriped muscle inthe scalp. These and other investigations into the 
involuntary muscular tissue convinced me of the correctness of KOLLIKER’s obser- 
vations, and led me to regard his discovery as one of the most beautiful ever 
made in anatomy ; and this is now, I believe, the general opinion of histologists. 
Still, however, there are those who are not yet satisfied upon this subject. In 
MiitLer’s Archives for 1854, is a paper by Dr J. F. Mazonn of Kiew, in which the 
author expresses his belief that the muscular fibre-cells of KoLLIKER are created 
by the tearing of the tissue in preparing it, and denies the existence of nuclei in 
unstriped muscle altogether ; but he gives so very obscure an account of his own 
ideas respecting the tissue, that his objections seem to me to carry very little 
weight, more especially as the appearances which he describes require, according 
to his own account, several days’ maceration of the muscle in acid for their 
development. In June of the present year (1856), Professor ELuis of University 
College, London, communicated to the Royal Society of London a paper entitled 
“Researches into the Nature of Involuntary Muscular Fibre.” In the ab- 
stract given in the “ Proceedings” of the Society, recently issued, we are informed 
that, “‘ having been unable to confirm the statements of Professor KOLLTKER re- 
specting the cell-structure of the involuntary muscular fibre, the author was in- 
duced to undertake a series of researches into the nature of that tissue, by which 
he has been led to entertain views as to its structure in vertebrate animals, but 
more especially in man, which are at variance with those now generally received.” 
In the “summary of the conclusions which the author has arrived at,” we find the 
following: “ In both kinds of muscles, voluntary and involuntary, the fibres are 
long, slender, rounded cords of uniform width ... .” “ In neither voluntary nor 
involuntary muscle is the fibre of the nature of a cell, but in both is composed 
of minute threads or fibrils. Its surface-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 appearance to the involuntary, and a transverse 
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 charac- 
ters to the corpuscles belonging to the yellow or elastic fibres which pervade va- 
