128 ENTOMOLOGICAL NEWS. [Mar., '15 



for identification. Not knowing the host or the habits of any 

 of the species, doubtless if dorsata and tnellitor were present, 

 he could not do otherwise than consider them identical and 

 as far as naming them is concerned it would be a matter of 

 history only. Or, if he thought it was really true that a dif- 

 ference in habit mattered here, he would be unable to decide 

 which is which. But this argument concerns practice only 

 and inconvenience and trouble in taxonomy must be courted 

 rather than avoided if there is a question of truth to be de- 

 cided. 



There can be no doubt that fundamental variation at first, 

 in many cases at least, is psychic the energy varies before 

 the substance and is infinitely more variable than the latter. 

 This psychic variation is inherited and forms habits and in- 

 stincts as in the insects. In simple forms of life, the differ- 

 ence in habit is not expressed morphologically as much as in 

 more complex forms, so that as we descend it becomes increas- 

 ingly more difficult to separate species morphologically and a 

 resort is made to their chemical nature and habits. But in 

 insects this is not true. The psychic variations may finally 

 become expressed morphologically and it is not until this is 

 done that a specific difference arises. Keeping in mind the 

 accepted meaning of species, we can point to many cases of 

 adaptive habit in various species, of insects. It is common and 

 nowhere else more so than with insect parasites. A parasite 

 of necessity has to adapt itself to the size of its host and I 

 have no doubt that the gregarious habit of the Bracon on 

 lepidopterous larvae is a case of this kind (obviously the 

 difference in host has no bearing on the matter). Even the 

 authors cited support my contention, for on page 66 (/. r.) 

 occurs this sentence: "It appears possible that the constantly 

 changing factors of nature cause the various species to be 

 continually adjusting their habits to new environments and 

 new hosts." And they cite examples of the adjustment to 

 new hosts. An adaptive habit is certainly not a basis for spe- 

 cific differentiation and we certainly must consider the social 

 or non-social habit of the Bracon as an adaptation to the size, 

 of its host. Even were it true that poly-embryony occurred 



