eee ae 
TT Beas The Ciliary Muscle. 219 
such as bring this force into active play from the extreme thinness 
of the films, the enclosing glass surfaces being probably not more 
than }oth of an inch apart. 
I regret that the small amount of time at my command avail- 
able for such studies has prevented me from pursuing the subject 
further. 
I purpose shortly to endeavour to examine the influence of the 
depth of graduated cells upon the quantity of crystals of the same 
and of various substances re-dissolved in given spaces of time, and 
to investigate the effect of capillary action on the solubility of salts 
under different conditions on a larger scale. 
The result, which I hope to communicate at a future time, will 
probably afford further confirmation of Mr. Sorby’s conclusion that 
“there is a direct correlation between mechanical force and the 
forces of crystallization and solution.” 
BirMinGuam, September 10, 1870. 
VI.—The Ciliary Muscle and Crystalline Lens in Man. 
By J. W. Houxss, F.R.CS., FBS. 
Part TT. 
(Continuation of Aris and Gale Lecture I.) 
Havine gained this insight into the apparatus of accommodation as 
it exists in the human eye, it will not be uninteresting to trace 
some of its modifications in other members of the vertebrate series. 
In all mammalia, monodelphous and didelphous, as far as my 
observations extend—and through the liberality of the Zoological 
Society of London, to which I am imdebted more than I can 
express, I have enjoyed unrivalled opportunities of examining the 
eyes of a large number of animals—the lens and ciliary muscle do 
not differ in any essential point from those of man. 
In mammalia generally the lens is more spherical than in man, 
In most the central planes are three, as in the human foetus; in a 
few (cetaceans and some rodents) there is but one primary plane. 
The capsule, its epithelium, and the lens-fibres, are essentially like 
those of man. The ciliary processes are simple, the suspensory 
ligament and its connections, the arrangement of the ciliary muscle 
and the kind of muscular tissue are such as we find in the human 
eye. 
Birds, however, present very striking differences. In a bird’s 
eye we are immediately struck with the great extent of the ciliary 
region compared with that occupied by the retina. It is the 
stoutest part of the outermost case of the eye-ball, its strength is 
