10 REPORT— 1858. 
structure, however, was so distinct, that I could measure the length of the central 
line, which was 0°0533, or =/5 of an inch. 
In four lenses which I examined three days after death, I observed fen septa on 
each side, but they had no resemblance whatever to the figure given by Dr. Young. 
The groups of fibres or vortices were like those of quadrupeds, with this difference, 
that the septa to which they were related were longer and much nearer the margin 
of the lens. These lenses were taken from male and female subjects about forty 
years of age. 
More recent observers have found equal difficulties in determining the true struc- 
ture of the human crystalline. Mr. Nunneley*, in his valuable paper on the crystal- 
line lens, lately published in the Microscopic Journal, makes the following remarks:— 
“« Tn the human lens the arrangement of the fibres is the most complicated of any, 
for while the type is the mammalian tripod, and is best seen in the foetus, in the adult 
the planes are more numerous, in consequence of the primary planes immediately 
branching into secondary, so that a very complicated curvature of fibres exists; the 
septa upon the two surfaces frequently not being equal, those of the posterior being 
more numerous than those of the anterior. In the anterior nine septa and radiations 
are often found, in the posterior surface ¢welve, which Arnold regards as the more 
common arrangement in man. This complicity, however, is only in the more super- 
ficial layers, for towards the axis the normal mammalian triseptal division is pre- 
served.” 
Mr. Nunneley does not inform us whether the statement that the structure varies 
in the same lens is founded on his own observations or on those of Arnold. Mr. 
Nunneley’s mode of observing consists in “immersing the lens for a few minutes in 
water at 180° Fahr.,”’ and after allowing it to dry in a warm room, he observes the 
number of sections into which it splits, and upon the supposition that it splits only 
in the direction of the septa, he infers the number of the septa from the number of 
these directions. We cannot place much confidence in results thus obtained. The 
lens, we think, should be studied in its entire state by following to their origin the 
converging or parallel fibres, by observing the changes in the diffracted spectra which 
they produce. By removing in succession the external layers, it will be easy to 
determine whether or not the structure changes in the layers near the axis. 
On the Crystalline Lens of the Cutile-fish. 
By Sir Davin Brewster, A.M, PRS. L. & EF. 
The crystalline lens of the Cuttle-fish differs in a remarkable degree from that of 
all other animals. Cuvier does not seem to have examined its structure. In his 
Memoir on the Mollusca, he merely gives a drawing of its external form, and 
mentions that it consists of two parts easily separated,—the anterior part being 
more convex than the posterior. In the new edition of his ‘ Lectures on Compara- 
tive Anatomy,’ published in 1845, the editors, MM. Frederick Cuvier and Lautillard, 
have repeated almost verbatim the description of the lens given in the original 
memoir {. 
Valentin, in Wagner’s ‘ Icones Zootomice §’, has given a section of the crystalline 
lens of the Cephalopods, which is repeated in Victor Carus’s ‘ Icones Zootomice ||.’ 
In this drawing the lens is represented as a sphere, the anterior part being much 
larger than the posterior. In his ‘ Lectures on Comparative Anatomy and Physiology 
of the Invertebrate Animals,’ Professor Owen describes the lens as Cuvier does, as 
consisting of two distinct parts, the anterior or smaller moiety being the segment of 
* In his more recent work, ‘On the Organs of Vision, their Anatomy and Physiology,’ 
plate 5, figs. 7 and 8, Mr. Nunneley has represented the human crystalline as having nine 
septa in its anterior, and ¢welve in its posterior surface. 
+ Journal of Microseopal Science, April 1858, No. 23, p. 150. 
t Ihave not seen the memoir of Muller in the ‘ Annales des Sciences Naturelles’ for 1831, 
on the structure of the eyes of the Mollusks; but as MM. Fred. Cuvier and Laurillard refer 
to it, I presume that it contains no additional information on the structure of the lens of the 
Cuttle-fish. 
§ Tab. 29. fig. 42. || Tab 23. fig. 1. Leipzig, 1857. J Sect. 24. p. 620. London, 1855. 
