Mr. Young's Observations on Vision. 177 
sued the hint, and probably for this reason, that from examin- 
ing only dried preparations, he has imagined that each coat 
consists of circumvolutions of a single fibre, and has intirely 
overlooked the attachment of the fibres to tendons ; and if 
the fibres were continued into each other in the manner that 
he describes, the strict analogy to muscle would be lost, and 
their contraction could not have that effect on the figure of 
the lens, which is produced by help of the tendons. Yet not- 
withstanding neither he, nor any other physiologist, has at- 
tempted to explain the accommodation of the eye to different 
distances by means of these fibres, still much anatomical 
merit must be allowed to the faithful description, and ele- 
gant delineation, of the crystallines of various animals, which 
he has given in the Philosophical Transactions, Vol. XIV. p. 
780, and Vol. XXIV. p. 1723. It appears, from his descriptions 
and figures, that the crystalline of hogs, dogs, and cats, re- 
sembles what I have observed in oxen, sheep, and horses ; 
that in hares and rabbits, the tendons on each side are only 
two, meeting in a straight line in the axis ; and that in 
whales they are five, radiated in the same manner as where 
there are three. It is evident that this variety will make no 
material difference in the action of the muscle. 1 have not 
yet had an opportunity of examining the human crystalline, 
but from its readily dividing into three parts, we may infer 
that it is similar to that of the ox. The crystalline in fishes 
being spherical, such a change as I attribute to the lens in 
quadrupeds cannot take place in that class of animals. 
It has been observed that the central part of the crystalline 
in our eyes, &c. Phil. Trans. Vol. XXIV. p. 1729. — CrystaUimun mmculum, 
alias humcrem crystallinum dictum, &c. Leeuwenh. op. omn. I. p. 102. 
