LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 13 
Hence it appears that the length of the most contracted 
fibre-cell is the same as that of the nucleus of an extended 
one. The fibres vary somewhat in breadth, independently of 
the results of contraction. Thus, one in the extended condi- 
* tion which I sketched, but which is not here shown, measured 
only 555 ich across. The nuclei of the uncontracted fibres 
are very constantly of the same length, and are good examples 
of the rod-shape to which Kolliker has directed particular 
attention. They always possess one or two nucleoli, and have 
often a slightly granular character; occasionally, as in fig. 21, 
they present an appearance of transverse markings. One 
frequently sees near the nucleus of a fibre that has been 
artificially extended from the contracted state, an appearance 
of a gap in the substance of the cell, forming a sort of exten- 
sion of the nucleus, asif the fibre generally had been stretched 
more completely than the nucleus. Mr. Ellis lays great stress 
on a dotted appearance which he considers characteristic of 
tavoluntary muscular fibre. I must say I agree with Kolliker 
in finding the fibre-cells, for the most part, homogeneous when 
extended, or faintly marked with longitudinal strie.* No 
doubt dots are present in abundance; but these, so far as I 
have observed them in the pig’s intestine, are distinctly exte- 
rior to the fibres, though adherent to their surface; and I 
suspect them to be little globules of a tenacious connecting 
fluid. 'That the fibre-cells do stick very tightly together, 
may be seen by drying a minute portion of the tissue, after 
which they will be found shrunk, and slightly separated from 
one another, but connected more or less by minute threads. 
To sum up the general results to which we are led by the 
facts above mentioned. It appears that in the arteries of the 
frog, and in the intestine of the pig, the involuntary muscular 
tissue is composed of slightly flattened elongated elements, 
with tapering extremities, each provided at its central and 
* The longitudinal stria above referred to, are probably due to a fine 
fibrous structure in the substance of the fibre-cells. When in London, last 
Christmas, I had, through the kindness of Dr. Sharpey, the opportunity of 
examining a specimen of muscle from the stomach of a rabbit; which he had 
prepared after Reichert’s method. The nitric acid had not only detached 
the fibre-cells from one another, but also brought out very distinetly in each 
muscular element the appearance of minute parallel longitudinal fibres, 
which seemed to make up the entire mass of the fibre-cell except the 
nucleus. Ina plate accompanying the paper on the Iris, before referred to, 
I gave figures of some fibre-cells with distinct granules arranged in longi- 
tudinal and transverse rows. This appearance, which, however, so far as 
my experience goes, is exceptional, and is hardly sufficiently marked to de- 
serve the appellation “dotted,” is probably caused by unequal contractions 
in the constituent material.—April 2d, 1857. 
