INTERNAL ANATOMY OF INSECTS. Ege 
the Jouse, the hive-bee, and several other insects, only a 
single nerve thus proceeds?; and in the larva of Ephemera, 
while ¢wo pairs issue from the six first ganglions, only a 
single one is emitted by the jive last. In the spinal mar- 
row of the rhinoceros-beetle, both larva and imago, the 
nerves consist of simple filaments which diverge like rays 
in all directions‘: the same circumstance distinguishes the 
cheese-maggot, only some of the nerves appear to branch 
at the end: in the louse, the last ganglion sends forth pos- 
teriorly three pairs of nerves which render to the abdo- 
men’. Sometimes, though rarely, nerves originate in 
the znternodes of the spinal marrow. Cuvier indeed has 
asserted that in invertebrate animals ad/ the nerves spring 
from the ganglions, and never immediately from the spi- 
nal marrow; but Swammerdam, in describing those of 
the silk-worm, mentions and figures four pairs as pro- 
ceeding from the four anterior internodes, excluding the 
first‘; and at the same time he gives it as his opinion, 
that all the nerves in insects really originate from the 
marrow itself, and not from the ganglions, which he as- 
serts are of a different substance, and are inclosed in the 
@ Prats XXI. Fic. 8. Swamm. Bibl. Nat. t. xxii. f. 6. 
b Jbid. t. xv. f. 6. ¢ Prate XXI. Fie. 7. 
2 Swamm. ubi supr. t. xlui. f. 7. h, h. 
© Prate XXI. Fic. 8. 
£ In Mr. Bauer’s figure (Philos. Trans. 1824. t. ii. f. 1.) no less than 
eighteen pairs of nerves are represented as issuing from the inter- 
nodes; but it should seem as if in the specimen from which his figure 
was taken, several of the ganglions, perhaps from some injury received 
in the dissection, had become obliterated, while their nerves remain- 
ed: yet still, even making allowance for these, many pairs will appear 
to take their origin from the spinal chord. 
VOL. IV. Cc 
