( kw ) 
this stage of life the insect is to a considerable extent an 
organism for the accumulation of property in the shape of 
unformed tissue: this unformed tissue is in the stage de- 
voted specially to development,—the pupal stage,—partly 
changed into the structures of the perfect insect, but in part 
carried over in the shape of still unformed tissue for the advan- 
tage of the final or reproductive period. But in the final stage 
of existence there is found a great change in the balance of 
the grand functions of life. There is a great demand on 
the organism by the function of reproduction ; the activity of 
the individual is much greater, the tracheal system facili- 
litating deterioration of the tissues is largely developed, while 
on the other hand, not only is there no corresponding im- 
provement in the modes for repairing waste, but there is an 
actual diminution of activity in this respect: many insects 
take little or no food while in the perfect condition, and it is 
probable that few take anything like enough to compensate 
for the great drain on the system during this stage, and they 
carry on the vital functions probably very largely by the aid 
of the unformed tissue they acquired during the earlier 
stage. 
This very rough and imperfect sketch enables us, I think, 
to,see that there may be direct relation between the lengths 
of the stages of the insect’s life. It will be in some respects, 
as we have previously seen, a disadvantage for the larval 
stage to be prolonged, but if the activity of the final stage is 
to be great, it is requisite that the larval stage should be 
sufficiently prolonged to allow of a large quantity of unformed 
material being carried over to the final stage; thus the 
strange paradox is established that limiting the activity in 
the final stage of the insect’s existence, other things being 
equal, will permit of the larva doing with a less amount of 
food,—that is, will allow it to shorten its period of existence. 
Now, is it not unreasonable to expect that under such circum- 
stances, during a long series of generations, an organism 
shall have developed any unnecessary variety of action ? 
Perfection within a limited range is what will be favourable 
to the continuance of the species. And this is the dominant 
feature of insect-instinct. 
