on the Mechanism of the Eye. 
name of a gland, as the greater part of the substances usually 
so denominated. In peeling it off, I have very distinctly observed 
ramifications, which were passing through it into the lens ; 
(Plate VI. Fig. 50.) and indeed it is not at all difficult to 
detect the vessels connecting the margin of the lens with its 
capsule ; and it is surprising that M. Petit should have 
doubted of their existence. I have not yet clearly discerned 
this crystalline gland in the human eye ; but I infer the existence 
of something similar to the globules, from the spotted appear- 
ance of the image of a lucid point already mentioned ; for which 
I can no otherwise account, than by attributing it to a derange- 
ment of these particles, produced by the external force, and 
*to an unequal impression made by them on the surface of 
the lens. 
In birds and in fishes, the fibres of the crystalline radiate 
equally, becoming finer as they approach the vertex, till they 
are lost in a uniform substance, of the same degree of firmness, 
which appears to be perforated in the centre by a blood vessel. 
(Plate VII. Fig. 53.) In quadrupeds, the fibres at their angular 
meeting are certainly not continued, as Leeuwenhoek imagined, 
across the line of division ; but there does not appear to be any 
dissimilar substance interposed between them, except that very 
minute trunks of vessels often mark that line. But, since the 
whole mass of the lens, as far as it is moveable, is probably 
endued with a power of changing its figure, there is no need 
of any strength of union, or place of attachment, for the fibres, 
since the motion meets with little or no resistance. Every 
common muscle, as soon as its contraction ceases, returns to 
its natural form, even without the assistance of an antagonist ; 
and the lens itself, when taken out of the eye, in its capsule. 
