on the human urethra . 
187 
request, extended them to the corpus spongiosum, and to the 
corpora cavernosa ; respecting the structure of which, even 
at this day, different opinions are entertained by some of the 
most celebrated physiologists in Europe. 
When these bodies are entirely empty and collapsed, as we 
generally find them in the dead body, they contract so much 
from their elasticity, as to make it next to impossible to ex- 
amine the structure of their different parts ; and no inconsider- 
able art and contrivance becomes necessary, so to prepare 
them, that the internal structure, may be sufficiently displayed, 
to render the examination satisfactory. Every attempt to make 
the substances commonly used as injections, pass from the 
arteries into the cellular internal structure, proved ineffectual ; 
that mode therefore of distending those cells was soon aban- 
doned ; injecting them directly by puncturing the surrounding 
coverings, could not give them their natural appearance ; we 
therefore did not avail ourselves of it. The only mode of 
expanding the internal structure, at the same time that it was 
not disturbed, was to fill it through the medium of its own 
arteries, and then, by hardening the parts in spirit, preserve 
them in a distended state. 
This was done in three different ways. In one instance 
they were found filled naturally, by the blood that had been 
retained there, and which, in the act of dying, had not been 
expelled, as in Plate XVIII. 
In another, proof spirit was injected by the arteries till all 
the internal cellular structure was distended by it ; and this 
spirit was retained there, as in Plate XIX. 
In a third, the arteries were injected with quicksilver, 
which readily passed into the internal parts, and was retained 
