12 LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 
forty-eight hours after death, I met with several good speci- 
mens of isolated fibre-cells. Though these fibres are very 
long, yet we have no reason to believe that anything near 
the extreme degree of extension has been attained in them, 
and we cannot but contemplate with amazement the extent 
of contractility possessed by this tissue. 
In one of the drawings is represented a portion of a fibre- 
cell curled up, which has been mtroduced for the sake of the 
clear. manner in which it shows the position of the nucleus 
imbedded in it. Just as in the case of the fibres wrapped 
round the arteries of the frog’s foot, this cell might be seen 
im section by proper adjustment, and that section is observed 
to be oval; proving that the fibre is not round, but somewhat 
flattened. It happens that the nucleus appears at this point ; 
its section is circular, and is surrounded on all sides by the 
substance of the cell. 
The pig’s intestine seems to be a peculiarly favorable situa- 
tion for the investigation of unstriped muscle. Judging from 
Kolliker’s measurements, the fibres appear to be of much 
larger size there than in the same situation in the human 
body. The length of the fibre-cell 3 is 3; inch. The fibre 
2 is imperfect at one extremity; but, taking the double of the 
distance from its pointed end to the nucleus, its length is 35 
inch. These measurements are between three and four times 
greater than any which Professor Kolliker has given for the 
human intestine, and considerably exceed the length of the 
“colossal fibre-cells ”? which he describes as occurring in the 
gravid uterus. The individual fibre-cells, with their nuclei 
and transverse markings, if they have any, are quite distinctly 
to be seen with one of Smith and Beck’s 34, object-glasses. 
But in order to examine their structure minutely, a higher 
power is required: that which I use is a first-rate +,, made 
several years ago by Mr. Powell, of London. The principal 
HN arg of the fibre-cells from the pig’s intestine are as 
under 
Length of fibre-cell, 3 - yy inch. 
Breadth of ditto ‘ : - 3500. 39 
Length of nucleus of ditto Iood » 
Breadth of ditto B000 9» 
Breadth of fibre-cell, 16 ‘ - 3000 0» 
Thickness of ditto . ; : : =d00 2» 
Length of fibre-cell, 13 ‘ > Fea OD 
Breadth of ditto : . Fede 
1 
Longitudinal measurement at nueleds of ditie sB00 
Transverse ditto 
Length of fibre-cell, 15 ual 
