6 
Sir Everard Home on the 
Below this is a regular line of ganglions, properly so called, 
being made up of a congeries of nerves, as the ganglions in 
the human body are now admitted to be. 
The brain appears to be made up of two lobes. The mass 
I call medulla spinalis, is also made up of two portions, uni- 
ted together by the two lateral chords. 
The ganglions down the body of the animal are united 
together by a double nerve. 
The annexed drawings show this structure better than can 
be explained by verbal description. Among the insect tribe 
the brain of the Humble Bee stands first, as being largest in 
proportion to the size of the body of the insect. Swammerdam 
has given a representation of the Bee ; it is in general correct, 
but not so in respect to the optic nerves. 
The Moth and Caterpillar have the same kind of brain, 
medulla spinalis, and series of ganglions, as in the Bee : the 
parts in the Caterpillar are nearly of the same size as in the 
Moth, but in both they are smaller than in the Bee. Swam- 
merdam has given a correct representation of these parts in 
the Caterpillar of the Silk- worm, but none of the Moth. 
The Lobster is similar in the structure of all these parts to 
the Bee, and although they are smaller in proportion to the 
size of the animal, they are still so large as to be readily 
seen, and explain what is not so distinct in the smaller insects. 
The Earth-worm has a brain and nerves formed upon a 
smaller scale, but made up of the same parts. 
In the Garden Snail, the brain and medulla spinalis are 
upon the whole larger in proportion to the size of the animal 
than in the Bee ; but in this animal, there are no ganglions, 
which may account for those parts being so large. 
