OF THE CRYSTALLINE LENS AFTER DEATH. 
255 
Both the lenses of the cow exhibited when taken out of the eye four beautiful struc- 
tures, in which the positive and negative structures alternate. The first and fourth 
were very faint, being the palest white of the first order. The third was also faint, but 
the second was both bright and large, and its tint was a brilliant yellow of the first 
order. After lying four days in water the lenses swelled so much that their dimen- 
sions were as follows : 
Inch. 
Diameter of one lens .......... 0-80/ 
Diameter of the other ......... 0*793 
Thickness of the first .......... 0*647 
Thickness of the second ....*.... 0*620 
The lenses were still transparent, and the tint of the structure No. 2 had risen to an 
orange red of the first order. 
Having experienced great difficulty in the course of the preceding experiments in 
preserving the capsule of the lens transparent for several days, I made trial of various 
fluids, but found distilled water more suited to my purpose than any other. I there- 
fore began a regular course of observations on the crystalline lens of the sheep when 
placed in distilled water, which have afforded me very satisfactory results. 
The lens of a sheep a year and a quarter old, when newly taken out of the eye, ex- 
hibited in the distinctest manner only one structure, with slight traces of an external 
one. This structure was positive , and occupied almost the whole of the lens, as shown 
in fig. 3. The traces of an external structure, when carefully examined, showed it to 
be negative. On the following day this lens burst in the direction of the three septa. 
In the lenses of another sheep I found two structures like the preceding, but with 
this difference, that the external negative structure was more developed, as in fig. 4. 
On the following day this negative structure had extended itself inwards, but in con- 
sequence of an accident the lenses burst their capsule. 
In the lenses of another Cheviot sheep, where the external negative structure had 
just begun to appear, the wide positive structure shown in fig. 3 had just begun to 
separate itself by a dark neutral line, which was seen only in one of its four sectors, 
and which divided that sector into two. 
In another Cheviot sheep the principal positive structure had distinctly divided 
itself into two positive structures, separated by a dark neutral ring, as shown in fig*. 5. 
The same appearance was shown in the other lens ; and I have found it a very com- 
mon structure in the lenses of sheep at that age when they are killed for the table. 
When this division of the principal structure takes place the central one is at first 
faint, and the other a bright white of the first order, as in fig. 4. It becomes, how- 
ever, brighter and brighter till it nearly rivals the other in the intensity of its polar- 
ized tint, as in fig. 5, when another change begins to show itself. 
This change, similar to that which I have described in the lens of the cow, arises 
from the absorption of distilled water by the capsule of the lens. It first shows itself 
