June, 1919 Bulletin of the Brooklyn Entomological Society 99 
relationships, its evidence must be tested by that from other 
_ sources stich as embryology, paleontology, the study of habits, 
etc., in addition to the study of the anatomy of larve, since it is 
only by obtaining the evidence from all possible sources, that we 
can arrive at the correct determination of the development and 
interrelationships of the different lines of descent among insects. 
It is not beyond the realm of possibility that in the polymorph- 
ism of such lower insects as the Isoptera, we have the beginnings 
cf a more pronounced metamorphosis in higher forms, since the 
tendency toward the production of different forms, instead of 
being scattered among different individuals (castes) in a species, 
might, so to speak, be gathered in the different stages of one 
individual. In the case of the South African butterfly Papilio 
merope, which has a male of one type, and females of other 
types differing among themselves very markedly in color and 
markings, there is one type of female which mimics a protected 
Acreid which is brown and yellow, while another type of female 
mimics a protected Acrzeid which is black and white. Both types 
of females may occur in the same brood, possibly as mutants ; but 
natural selection would tend to preserve the appropriately col- 
cred and marked type of female in that region in which its par- 
ticular model is the predominant form. In a somewhat analo- 
gous fashion, there may eventually have arisen among primitive 
insects in which there was already present a tendency to assume 
a slightly different “larval” condition (e. g., as occurs among 
Odonata, Plecoptera, etc.) certain new types which differed quite 
markedly from the adults in their immature stages—these new 
types possibly arising as mutants. At any rate, these changes 
probably arose from within rather than owing their origin to 
wholly external influences although it is impossible to determine 
in some cases, how much the environment may have influenced 
the germ plasm itself. 
As long as insects in their immature stages are so to speak 
small replicas of the adults, they are no better fitted than the 
adults themselves for invading and establishing themselves in 
new media (woody tissue, etc.) or in new regions where existence 
is precarious. Similarly, unless suitable instincts were developed 
in conjunction with the proper bodily structures, such forms 
