5 
internal structure of the human brain, &c. 
arrived at a like excellence in the use of the microscope ; for 
certainly Poli (however splendid his plates) cannot be put 
in competition with either of them. 
When Swammerdam died, and no one found himself equal 
to succeed him, a report was raised that his microscope was 
of a peculiar kind, and the mode of using it was lost at his 
death ; so it is now with Bauer. Many applications are made 
to the mathematical instrument makers for a Bauer’s micro- 
scope, by those who are not willing to believe it is their in- 
ability, and not the fault in the microscope, that prevents 
their arriving at his excellence. 
In all the insect tribe I have examined, the brain is formed 
upon the same general principle, but very different from that 
of fishes ; the brain is in one mass ; it is too small to admit of 
a particular description, but contains globules ; and from the 
readiness with which it dissolves upon exposure, there is no 
doubt of there being a fluid contained in it. Besides this, which 
is admitted to be the brain of the insect, there is another sub- 
stance connected to it by means of two chords. This second 
part has been, I believe, usually called the first ganglion, but, 
when accurately examined, it is similar in its texture to the 
brain: the two chords which unite them are not properly 
nerves, since they are upon their first exposure turgid, but soon 
collapse. These two substances with their uniting chords form 
a circle, and surround the oesophagus ; from the upper mass 
go off the optic nerves, those to the tentacula, tongue, &c. 
From the lower mass go off the nerves to the upper ex- 
tremities. 
I shall therefore consider the upper as the brain, the lower 
as the medulla spinalis. 
