BY MOLECULAR COALESCENCE. 149 
mass, but in the latter—the lens—being limited only to very 
small portions of lens-substance. It must also be observed 
that the process of coalescence is accompanied by a che- 
mical change in these albuminous globules, as is shown 
by boiling a lens for a considerable time in water, when 
the peripheral and imperfectly coalesced portion will by 
its opacity indicate the presence of coagulated albumen, 
whilst the central and adjoining parts will retain their trans- 
parency, thus seeming to partake more of the character of 
horn than of coagulated albumen. Now, on reviewing this 
account of the formation of the crystalline lens of the 
fish by the process of molecular coalescence, and con- 
trasting it with the simple manner in which artificial 
globules of the same size, as well as the otolithes of 
these same fish, are formed (which can be shown to be 
formed by coalescence), this will appear to be a very 
round-about way of making a globular body, which ac- 
cording to the explanation of the mode of formation of 
artificial and other calculi, seems possible by a method so 
very simple and direct. And if such transparent globules 
as those produced by the artificial process could have 
served for the purpose of vision, this objection would have 
been just. But these former giobules being of necessity 
so formed that their centre is the least dense, and their 
circumference most so,—a form of construction exactly the 
reverse of that of the lens,—could never have sufficed to 
bring the rays of light to a focus, and therefore they 
would be totally unfit for vision. Hence when vitality is 
engaged in constructing such a lens as that just described, 
and the principle of universal attraction has to take chief 
part in the process, the tendency of this attraction to form 
just such a lens as that which would be constructed by the 
artificial process will require at every instant to be opposed. 
