9 
on the Structure of Nerves. 
them, the chances of error were few; since the person who 
first observed the appearances had no previous opinions on the 
subject; and Mr. Ramsden was better able than any other 
person, to correct such optical errors as might deceive Mr. 
Clift or myself. 
The first experiments were made upon transverse sections 
of the nerve. One, near its termination in the eye, was placed 
upon glass, and exhibited in the microscope the following ap- 
pearances : it was evidently composed of two parts, one opaque, 
the other transparent. The opaque portions were nearly cir- 
cular in their shape, about 600 in number, and touched one 
another; the interstices between them were transparent. 
When the opaque parts were attentively examined in a favour- 
able light, and the nerve was in a recent state, they were found 
to be made up of a great number of smaller portions, each of 
which appeared to be also opaque. To see this subdivision of 
parts required some attention, and in many sections it could 
not be perceived. The cause of the difficulty seemed to be* 
the softness and tenacity of the substance divided, which 
therefore spread itself over the surface, giving it an uniform 
appearance ; but, towards the circumference of the nerve, where 
the parts were cut obliquely, and some of them torn, the sub- 
division was very distinct. It was first observed by Mr. Clift, 
in several different sections ; and was afterwards seen very dis- 
tinctly, both by Mr. Ramsden and myself, in a nerve examined 
about two hours after death. 
Having repeated these experiments six or seven times, on 
different days, so as to ascertain the accuracy of the results, 
the next object was, to determine whether the nerve had the 
same structure in its whole course. For this purpose, trail s-- 
MDCCXCIX. C 
