STRUCTURE OF THE CRYSTALLINE LENSES OF ANIMALS. 
41 
the cat ; but Leeuwenhoek committed the strange mistake of supposing that each 
coat or lamina of the lens consists of circumvolutions of a single fibre, whereas each 
fibre has a distinct termination in the septum at both its extremities. Dr. Thomas 
Young seems to have been occupied with the examination of the crystalline lens of 
the ox in 1792 or 1/93, previous to the publication of Sattig’s thesis ; and in his ob- 
servations on Vision, read before the Royal Society on the 30th of May, 1/93, he has 
given a drawing and description of the result of his observations*. This description is 
exactly the same as that previously given by Leeuwenhoek, excepting that Dr. Young 
erroneously maintains that each of the coats of the lens “ consists of fibres intermixed 
with a gelatinous substance,” which we presume he considered to be necessary for 
cementing the fibres into a compact body. 
In Dr. Young’s subsequent and more elaborate paper on the Mechanism of the 
Eye'f~, he renounces as erroneous the description which he had given of the arrange- 
ment of the fibres in the crystalline of the ox ; and he substitutes, in place of his 
former correct drawing, another, which is altogether visionary. “ In man,” says he, 
“ and in the most common quadrupeds, the structure of the lens is nearly similar. 
The number of the radiations is of little consequence ; but I find that, sometimes at 
least, in the human crystalline there are ten on each side, not three, as I once, perhaps 
from a too hasty generalization, concluded. Those who find any difficulty in disco- 
vering the fibres must have a sight very ill adapted to microscopical researches.” 
Notwithstanding the assertion in this passage that the structure of the lens in man 
and the most common quadrupeds is nearly similar, yet fig. 93, in which he represents 
“ the order of the fibres of the human crystalline,” is essentially different from fig. 95, 
in which he shows the u ramifications (of the fibres) from the margin of the crystal- 
line lens” in quadrupeds. In the first of these figures there are no ramifications of 
the fibres from the margin of the lens, Avhereas in the second there are no fewer than 
six, placed without any symmetrical relation either to the septa or to one another. 
The following Table contains the names of the different animals in whose lenses I 
have found the structure shown in Plate V. figg. 1, 2, and 3. These animals are 
all quadrupeds, with the exception of the anonymous fish caught near the Azores, to 
which I shall have occasion again to refer X- 
Lion. Ox. Goat. 
Tiger. Cow. Sow. 
Horse. Sheep. Deer, Fallow. 
* Elements of Natural Philosophy, vol. ii. p. 525. “ In examining,” says he, “the crystalline from an ox, 
I discovered a structure which appears to remove all the difficulties with which this branch of optics has long 
been obscured.” 
f Elements of Natural Philosophy, vol. ii. p. 597. 
1 For the lenses of several of the rarer animals contained in the following Table, I have been indebted to 
the liberality of the Zoological Society of London. 
MDCCCXXXVI. G 
