articulated appendages, the legs and wings, 
must undergo a still further improvement, and 
the means whereby this is accomplished are 
sufficiently manifest. The nervous ganglia are 
accumulated into a few large and powerful 
centres of innervation; the rings of the body, 
to which the locomotive organs are attached, 
are dilated and strengthened in proportion to 
the force of the muscles placed within, and 
constitute three thoracic rings of such firmness 
and inflexibility that they may well be looked 
upon as forming a distinct division of the exo- 
skeleton, and give rise to the distinction laid 
down by entomologists betweeen the head, the 
thoracic, and the abdominal segments that enter 
_ into the composition of an insect’s body. But 
_ the same concentration of the nervous system, 
which permits an Insect to possess the extraor- 
dinary powers of flight with which it is gifted, 
allows by the increased perfection given to 
the brain, the possession of elaborately con- 
Structed senses. The eyes assume a complexity 
of structure that is truly wonderful, the sense 
_of touch attains extreme delicacy, and indubita- 
bly the means of smelling, of tasting, and of 
hearing are now conferred, however incapab'e 
we may be of pointing out the mode in which 
_ they are exercised ; nay, it is extremely proba- 
ble that capabilities of perception of which we 
_ can form no idea, are bestowed upon the Insect 
‘Faces commensurate with the activity of their 
movements and the wide range of duties they 
are appointed to perform. 
_ During the metamorphosis to which Insects 
are subject, that is to say during the advance- 
ment of these creatures from an embryo condi- 
m to their mature or perfect state, changes 
are constantly in progress, both in the nature 
and arrangement of the locomotive organs, and 
of course as these changes are effected, the 
entire disposition and even the vital properties 
of the muscular system oa elghats to their 
movements undergo a considerable modification. 
larvee of many genera have externally the 
_ appearance of the simplest worm, being pro- 
_ vided with not even any vestiges of the loco- 
Motive apparatus that subsequently is to be 
Mevelopet : even the rings or segments of the 
_ body are entirely soft, the cuticular covering 
__ being of extreme tenuity, and the tegumentary 
_ muscles, as a natural consequence, propor- 
__ tionally rudimentary in their structure. In 
‘| _ Such larve the nervous system exhibits the 
____ lowest condition found among the apodous An- 
__helidans, and the eyes and external senses are, 
if they exist at all, of the humblest possible 
character. This is the case, for example, in 
the maggots of many Dipterous and Hymenop- 
terous Insects. 
__In others, as for instance in the caterpillars 
of the Lepidoptera, the locomotive powers are 
of a slightly ameliorated description : the larva 
Possesses a distinct head, and to the succeeding 
‘Segments, rudely constructed limbs named legs, 
and others bearing still less resemblance to the 
locomotive members of the future insect, to 
which the name of pro-legs has been appro- 
elie are the only instruments of progression, 
ven in the most perfect larve, as in those of 
rh, ol 
MUSCULAR SYSTEM. 
539 
the aquatic Beetles, the form is elongated and 
resembles that of an Annelidan; the legs are 
comparatively feeble and of small size, and 
simple ocelli replace the compound eyes that 
afterwards become developed in the perfect 
Insect. 
During the progress of the metamorphosis, 
the nervous system within is undergoing a pro- 
cess of concentration precisely comparable to 
that which has been noticed in advancing from 
the lower to the higher classes of ArTICULATA. 
The ganglia coalesce and become less numerous, 
the encephalic pair attain a higher development, 
and as this is accomplished the legs and wings 
of the mature being sprout from the sides of 
the segments appropriated to sustain them, 
enclosed in and defended by cases of cuticle 
temporarily provided, which constitute the 
covering of the pupa or chrysalis, until at 
length, the aggregation of the previously sepa- . 
rated ganglia being completed and the brain 
perfected to the extent required, the pupa-case 
is thrown off, the newly-formed limbs expand, 
and the insect, with its newly-acquired limbs, pos- 
sesses an additional system of muscles, which 
have been developed with their growth, and 
only arrive at their full state of perfection when 
the body has ceased to grow, and the genera- 
tive system, having attained its complete pro 
portions, proclaims the animal mature and able 
to propagate its species. 
The addition of wings, indeed, to the body 
of flying insects would seem to be a provision 
specially connected with the distribution of the 
progeny to which they are to give birth, and all 
the phenomena connected with their develop- 
ment and that of the muscular appar itus pro- 
vided for their movements to have relation to 
this great and closing act of the insect’s exist- 
ence. The period of time during which these 
animals live in their imperfect or wingless state, 
during which many of them have important 
offices assigned to them, constitutes, in most 
cases, by far the longest portion of their lives, 
and some aquatic larve, indeed, reside for 
months or even years in the water under their 
immature or wingless form, which perish in a 
few hours after they have been gifted with the 
means of aerial locomotion. Had they never 
been furnished with wings, it is abundantly 
evident that the species of such insects could 
never have been dispersed beyond the precincts 
of the pond or the ditch in which the parent 
had passed her existence, but the brief space 
allowed them to enjoy life in the winged con- 
dition is sufficient for the achievement of the 
great object in view, and the Ephemeron and 
the little Gnat, while they appear to be only 
sporting out their evening’s life amid the sun- 
beams, are, in fact, disseminating their offspring 
through different localities. 
The next class of HomoGanGLiaTe animals 
comprises the ARacHNIDANS, the Scorpions 
and the Spiders, animals visibly intended 
to be destroyers, appointed to keep within 
due limits the different races of the Insect 
world, and by assisting in the great work 
of destruction that is on all sides in progress 
against them, to prevent their fertility from 
