192 Dr. Haighton's experimental Inquiry 
function. It supposes likewise (and which by the way is not 
true), that anatomists are perfectly agreed upon this matter; 
and that those who make their appeal to anatomy, have ad- 
mitted a common standard of comparison, by which they allow 
their experiments to be judged ; but no position is more remote 
from fact. It is sufficient to say, thatsome think ultimate nervous 
fibres are constructed to act by tremors, whilst others believe 
them to be hollow tubes. Nor is the difference of opinion less, 
respecting the appearances which they exhibit on being viewed 
by a microscope. One eminent physiologist* observes, that 
the ultimate nervous fibres are “ serpentine and convoluted, 
“ very much resembling the winding of the seminal ducts in 
“ the testicle, or epididymis:" but having extended his micro- 
scopical observations to other parts, he finds a similar disposi- 
tion of fibre ; nay, even neutral salts, in a state of crystalli- 
zation, and metals, when microscopically examined, have 
convoluted fibrous appearances, corresponding with those of 
nerves. Another ingenious inquirer, -f having subjected the 
nerves to microscopic examination, thought at one time that 
their fibres were composed of cylinders, with bands twined 
around them, in a spiral direction ; but subsequent examina- 
tions convinced him, that this appearance had its origin in an 
optical deception, and that their true direction was that of 
" parallel winding fibres." I have not yet heard whether a 
third examination has rectified the errors of the two former. 
As it appears then, that microscopical observers neither 
agree with each other on this subject, nor with themselves, I 
think it fair to conclude, that ocular inspection cannot be ad- 
mitted as a fair appeal, from which we can determine whether 
-f- Fontana-. 
Dr. Monro. 
