18 INTERNAL ANATOMY OF INSECTS. 
marrow for the sake of giving it greater firmness*. In 
this opinion, however, he seems singular>. ‘Those re- 
markable nerves described by Lyonnet under the name 
of spinal bridle (bride épiniére) also take their origin, not 
from the ganglions, but from a bifurcation of the spinal 
marrow. Of these, in the caterpillar of the goat-moth 
there are fen, the first issuing from the bifurcation of 
the internode between the fourth and fifth ganglions, and 
the remainder from the succeeding ones. After approach- 
ing the succeeding ganglion, these nerves form a pair of 
branches that diverge nearly at right angles from the 
bridle, and producing several lesser branches, lose them- 
selves in the sides of the animal*. Besides the nerves 
above-mentioned, two generally issue from the poste- 
rior part of the last ganglion, diverging in opposite and 
oblique directions: some of these render to the parts of 
generation; and in the silk-worm, and probably other 
species, the innermost pair is perforated for the passage 
of the vasa deferentia4. 
After duly considering this general outline of the ner- 
vous system of insects, the question will continually oc- 
cur to you,—is then what you have called the brain the 
sensorium commune of these animals, in the same manner. 
as it isin those with warm blood? To this query a ne- 
gative must be returned. In the latter, the brain is the 
common centre to which, by means of the nerves and 
* Comp. Cuv. Anat. Comp. ii. 102—123.; with Swamm. Expl. of 
Plates xxxii. ¢. xxviii. f. 3. &. 
>» Malpighi seems, however, to agree with him. De Bombyc. t. vi. 
pale © Lyonnet whi supr. 201. t. ix. f. 1, 2. n. 1, 2. &e. 
4 Swamm. abi supr. 1. 139. a, t. xxviii. fi 3. s,s. 
