1878.] | Phosphorescent Insects. Their Metamorphoses. 357 
responding alterations in many of its parts in conformity with the 
new conditions of its existence. In accordance with the laws of 
adaptive evolution, large eyes, embracing great areas, either in 
pursuit or avoidance of rapidly-moving objects on the wing, being 
no longer of use in this degraded position, where they could 
neither aid the insect’s flight nor assist it in procuring sustenance, 
would gradually be replaced by less globular ones with smaller 
lenses suited to nearer views. If this degradation were sudden 
it would be attended with great mortality; hence we find few 
beetles to be apterous, indicating, in my opinion, one of two 
probabilities, either that they are unable to sustain the rapidity of 
the change, or that being a comparatively recent evolution they 
have not yet attained numerical importance. 
According to Mr. Felix Plateau, the centre of gravity differs in ' 
the larva and imago of insects, being effected by the coincident’ 
enlargement of the thoracic and the diminution of the abdominal 
segments. This fusion of segments and their ganglia, in view of 
the part they play in supplying the legs and wings with their 
suitable nerves of sensation and motion, having adapted the cen- 
tre of gravity to given conditions, there would be a proper equi- 
poise in all the parts. It can easily be seen that upon a change 
from the winged to the apterous type, if this were comparatively 
sudden, the body would be unwieldy, and the disproportion be- 
tween the parts, rendering the creature’s motionS heavy, would 
tend to the non-use of the feet, and the consequent enfeebling of 
these members. Being unable.to travel far in quest of food the 
insect would from necessity have less opportunity of feeding,.thus 
aborting the manducatory organs from want of use. The chances 
of individual life being thus diminished the apterous female 
would no longer exist for herself but, supporting life , from 
material probably stored up in the more active larval stage until 
she had deposited her eggs in a suitable nidus, would then expire, 
having completed her mission of race-preservation. 
In thus treating of what might be expected from an insect 
having certain powers of adaptation, I have followed the order as 
indicated in the different characters seen in Lampyris., I have 
traced it in its supposed evolution from an apterous to that of an 
«rial being, and back to earth again as a creeper with heavy dis- 
proportioned body, feeble feet and mandibles, small eyes, and 
brilliant terminal segments. 
