CONTRACTILE TISSUE OF THE IRIS 3 
An operation for artificial pupil, by excision, performed by Mr. Wharton 
Jones, at University College Hospital, on the 11th of August of the present 
year (1852), placed in my possession a perfectly fresh portion of a human iris, 
and, without knowing that Kolliker’s observations had extended to the muscles 
of the eye, I proceeded to avail myself of this somewhat rare opportunity of 
investigating the muscular tissue of the human iris. On placing under the 
microscope, four hours after the operation, portions of the tissue carefully 
teased out in water with needles, I found that some of the muscular fibre-cells 
had become isolated, and presented very characteristic appearances. I accord- 
ingly made camera-lucida sketches of the finest specimens, which are reproduced 
on a smaller scale in the accompanying figures (see Pl. I, A, Figs. 7-11). I drew 
the last cell (Fig. 8) nine and a half hours after the operation. And here I may 
mention that I have not found the muscular fibre-cells by any means a very 
perishable tissue. After an iris has been soaking two or three days in water, 
the muscular tissue of the sphincter is still quite recognisable, not only by 
the nuclei, but also by the individual fibre-cells. 
Of the figures above referred to, (7) and (8) are examples of the most 
elongated cells that I saw. By reference to the scale it will be found that the 
cell (7) is about 1-125th of an inch in length, and about 1-3750th of an inch 
in greatest breadth ; while (8) is a little shorter, but of about the same average 
breadth. Kolliker divides muscular fibre-cells into three artificial divisions, 
according to their shape, of which the third contains the most elongated and 
most characteristic cells. Of this third division, the cells (7) and (8) are good 
examples, and, in fact, correspond in their measurements to average fibre-cells 
of the muscular coats of the intestines. The cells (9) and (10), though less 
characteristic in respect of their length—(g) being about 1-333rd of an inch 
in length, and r-3000th of an inch in breadth, and (10) 1-300th of an inch by 
I-3000th of an inch—yet present the same peculiar delicate appearance and 
soft outline, and the same elongated nucleus, of not very high refractive power 
relatively to the contents of the cell, but clearly defined. All these cells have 
the same flat or ribbon-like form which is exhibited by the cell (8) at @, where 
one edge has become turned up by a folding of the cell; at 5 there seemed 
a tendency to transverse arrangement of the granules of this cell, which ten- 
dency is more strikingly exhibited at } and c in the cell (11), which, though not 
isolated, is introduced on that account. This tendency to transverse arrange- 
ment of the granules was long since noticed by Mr. Wharton Jones, as that 
gentleman has since informed me, and is, indeed, indicated in the drawings 
which are alluded to in the note above. In the cells of this iris, however, it was 
not by any means constant. Some of them, as (7) at a, and (9) at a@ and 8, 
B 2 
