356 NERVOUS SYSTEM OF ARTICULATED ANIMALS. 
the Moth being much shorter than that of the Caterpillar), 
and that great changes have taken place in the relative sizes 
of the ganglia. The cephalic 
ganglia, being now connected 
with much more perfect eyes and 
other organs of sense, are greatly 
enlarged ; the thoracic ganglia, 
1 from which the legs and wings 
- are supplied, are enlarged and 
? — concentrated ; whilst the abdomi- 
{nal ganglia are relatively dimi- 
é nished in size, the 7th and 8th 
7 
2 
being entirely wanting. 
442. When the structure of 
ake, the chain of ganglia is more par- 
a +~ to consist of two distinct tracts ; 
9 7kK.—"° one of which is composed of 
~ s—S4; ‘nervous fibres only, and. passes 
= 10 ee backwards from the cephalic 
12 ganglia, over the surface of all 
SY 11 13° the ganglia of the trunk, giving 
; off branches to the nerves that 
Se 2 proceed from them; whilst the 
13 other connects the ganglia them- 
selves. Hence, as 2 Mollusca, 
‘ , __ every part of the body has two 
yous Srerew ov we er as sets of nervous pee r = 
ARVA OF SPHINX SPHINX with the cephalic n ia, the 
LIGUSTRI, LIGUSTRI. other with asa caingibn of its 
own segment. Impressions made upon it, being conveyed by 
the fibrous tract to the cephalic ganglia, become sensations; and 
by the influence of the conscious power, operating through 
these same ganglia, the general movements of the body are 
harmonised and directed. It is obvious that, as the motions 
of an animal are chiefly guided by its sight, the cephalic’ 
ganglia would have a governing influence over the rest, if 
only from their peculiar connexion with the eyes; but there 
is good reason to believe that their functions are still more 
different from those of the ganglia of the trunk, and that 
sensation resides in them alone. The motions produced by 
9 ticularly inquired into, it is found ~ 
ee 
a i a i lt 
i ee 
