Dr. Young's Lecture 
74 
filled with cool, and then with warmer water: a plane speculum 
was placed under it ; a perforation in the bottom was filled with 
a plate of glass ; proper rings were fixed for the reception of 
the lens, or of the whole eye, and also wires for transmitting 
electricity : above these, a piece of ground and painted glass, 
for receiving the image, was supported by a bracket, which 
moved by a pivot, in connection with a scale divided into fif- 
tieths of an inch. With this apparatus I made some experi- 
ments, assisted by Mr. Wilkinson, whose residence was near 
a slaughter-house : but we could obtain, by this method, no 
satisfactory evidence of the change ; nor was our expectation 
much disappointed. I understand also, that another member 
of this Society was equally unsuccessful, in attempting to pro- 
duce a conspicuous change in the lens by electricity. 
XI. In man and in the most common quadrupeds, the struc- 
ture of the lens is nearly similar. The number of radiations is of 
little consequence; but I find that in the human crystalline there 
are ten on each side, (Plate VI. Fig. 46.) not three, as I once, 
from a hasty observation, concluded* Those who find any 
difficulty in discovering the fibres, must have a sight very ill 
adapted to microscopical researches. I have laboured with the 
most obstinate perseverance to trace nerves into the lens, and 
I have sometimes imagined that I had succeeded; but I cannot 
positively go further than to state my full conviction of their 
existence, and of the precipitancy of those who have absolutely 
denied it. The long nerves, which are very conspicuous be- 
tween the choroid and sclerotic coats, divide each into two, 
three, or more branches, at the spot where the ciliary zone 
begins, and seem indeed to furnish the choroid with some fine 
• De Corp. Hum. Vir. Cons. p. 68. 
