I 244 ] 
upon the membrana tympani, are extended 
to the brain? And how all the other im- 
preffions on the nerves are communicated 
to the fenforium ? 
For the folution of this problem, New¬ 
ton had recourfe to the ofcillations of the 
aether, which, according to this great 
philofopher, was the caule of all the mo-> 
tions of the univerfe. But as this aether 
is not known, and as electricity explains 
thefe phenomena fufficiently well, we fhall 
fubftitute the laft mentioned agent for the 
aether of Newton. 
Since the medullary fubftance of the 
brain is of a fibrous compofition, the 
threads of which are difpofed in a paral¬ 
lel direction, as is particularly obvious 
even to the naked eye in the corpora ftriata, 
the thalami of the optic nerves efpecially 
of fifhes, in the fornix, when immerfed 
in nitrous acid for fome time ; fince there 
are nerves in which thi? compofition is 
fufficiently 
