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 Kolliker'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 pupillae 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 Kolliker's recent dis- 

 covery of the " arrectores pili," and describing the distribution of those little 

 bundles of unstriped muscle in the 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 

 Muller'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 Ellis 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- 



