STRUCTURE OF THE CRYSTALLINE LENSES OF ANIMALS. 
45 
Hence it is obvious that the crystalline lens of the elephant differs from that of 
most other animals, in being of an elliptical form, the horizontal diameter of the 
ellipse being the longest. 
When the lens has been preserved in spirits, and the outer coats are removed, it 
resembles a piece of the finest amber. In this condition, when dry, it does not crack, 
like other lenses, but exfoliates in thin scales, which give it the appearance of a flat 
pearl. When these scales are rubbed off it resumes its appearance of amber, and 
when well dried, after two or three exfoliations, it becomes as permanent in its ap- 
pearance and colour as that substance, and almost as hard and durable. 
This peculiar property of the elephant’s lens arises from the peculiar structure of 
its coats or laminae. These coats are not, properly speaking*, composed of fibres, but 
are of a fibrous tissue, the elementary fibres of which are not united mechanically 
by teeth, but by some other process, probably that of agglutination, which I cannot 
discover by the finest microscopes which I possess *. 
Owing to this structure of the laminae, the superficial colours are not displayed, as 
in other lenses, and it is very difficult to trace the elementary fibres into the septa, to 
which they are related. I have succeeded, however, in determining that there are six 
radiations of fibres and three centres of divergence on each surface of the lens. 
This structure is shown in Plate VI. figg. 5 and 6, in which there are three septa 
diverging from the poles of the lens, as in quadrupeds, and from the extremity of 
each two additional septa, which are the real septa, to which the fibrous radiations 
are principally related. The three central septa are inclined 120° to each other, and 
the two additional septa seem to be inclined at an angle of 60° to each of the central 
ones ; but these measures are of course only rude estimates of the inclination of lines, 
which in animal and vegetable organizations, and even in those of the mineral world, 
approximate only to the mathematical type of their characteristic structure. 
In the combination of fibres shown in figg. 5 and 6, there are twelve fibres whose 
parts all lie in the same plane, all the rest forming curves of contrary flexure. 
In some lenses of the elephant, I have found the three septa which meet in the 
poles of the lens exceedingly small, and approaching to evanescence ; and I have no 
doubt that, as happens in the case of four septa, these three central septa will in some 
lenses be wanting ; so that the other six septa will diverge from the poles at angles 
of 60°, like the radii of a hexagon. Such a lens will bear the same relation to the 
structure shown in figg. 5 and 6 as the structure in figg. 1 and 2 bears to that in 
figg. 3 and 4. 
* In extremely thin and highly-dried fibres, the fibres are better seen with the microscope ; and I have ob- 
served something like a mechanical union of them. 
