of the Crystalline Lens after Death. 195 



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 pre- 

 ceding experiments in preserving the capsule of the lens trans- 

 parent for several days, I made trial of various fluids, but found 

 distilled water more suited to my purpose than any other. I 

 therefore 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, exhibited in the distinctest manner only 

 one structure, with slight traces of an external one. This struc- 

 ture 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 

 consequence 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 common 

 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, however, brighter and 

 brighter till it nearly rivals the other in the intensity of its po- 

 larized 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 by the appearance 

 of a brown tint in the dark neutral ring which separated the two 

 positive structures. In the middle of the brownish-black ring 

 a trace of feint bluish Light appears, generally in one ©f the sec- 

 tors only, but gradually extends itself into a blue ring, which 

 has negative double refraction, and which is separated by di- 



02 



