4 
Sir Everard Home on the 
In the representation of the brain of the Tench, which is 
annexed, there is evidently a smaller quantity both of medul- 
lary and cortical substance in proportion to the size of the 
animal than in the bird, and its form is less compact, being 
made up of spherical nodules, medullary on the surface, and 
internally cortical : the basis of the brain is also nodulated, 
and in the centre is an oval cavity. The nodules are upon so 
small a scale that their internal cavities are not to be distin- 
guished, but in the squalus maximus they are very conspi- 
cuous. I am now to point out the peculiarities of the brain 
in insects and worms ; but cannot tread upon the same ground 
on which Swammerdam has preceded me, without paying a 
tribute of praise to that great man, who, labouring under such 
disadvantages as he must have done, in the age in which he 
lived, has performed so much, and in many instances has left 
nothing for those who follow him, but to bear testimony to 
the correctness of his representations and judgement. 
There are some points in which he gave way to public 
opinion, and did not disbelieve what every one said must be 
true. I allude to his attempt to represent the eye of the 
garden snail at the point of the horn, which does not exist. 
He found black retemucosum, which he mistook for nigrum 
pigmentum, and a pellucid part which he took for cornea. 
To show this fallacy, I have annexed Mr. Bauer’s represen- 
tation of these parts. Swammerdam has given a faithful 
representation of the nerve, which might have undeceived 
him, it having no resemblance to other optic nerves, but being 
like those commonly met with going to tentacula. 
It is curious, that long as has been the intervening period 
of time between Swammerdam and Bauer, no one has 
