444 annual report Smithsonian institution, 1918. 



the snialler carnivor ; the carnivor increased its strength in order to 

 be in condition to overpower the larger prey which was slipping 

 away from it. And thus continued step by step the struggle, a con- 

 tinuous open struggle, which resulted in the gigantic and highly 

 specialized forms. But conditions of existence changed and the mas- 

 sive specialized animals were not able to obtain the necessary plastic- 

 ity and adaptability, and died out, completing in themselves the 

 chain of development of separate groups. Such is in general the 

 process of evolution of the external appearance of the type of verte- 

 brates. 1 



We will now pass to the insects. To keep abreast of the verte- 

 brates, by developing the massiveness of form, they were evidently 

 unable to do. The very brevity of their life cycle with the usually 

 rapid cessation of growth gave them no hope of conquering even a 

 jnodest position for themselves among the increasingly developing 

 vertebrate classes. It would seem their fate was doomed beyond 

 hope. But in the struggle for existence nature recognizes no honor- 

 able or dishonorable means ; all of them are good if they lead to the 

 purpose, and where nothing can be taken b}^ force she takes things 

 by the aid of trifles, converting these trifles into a mighty power. 

 If the struggle can not be direct it becomes necessary to dodge it. 

 And thus, with this method, diametrically opposed to the preceding, 

 the evolution of insects proceeded. 



The world is occupied by large, ponderous vertebrates, engaged in 

 a keen struggle with one another, and to keep up with them there is. 

 absolutely no possibility; but everywhere among them there re- 

 main small free nooks, whither it is useless for the heavy ponder- 

 ous vertebrates even to think of penetrating. It is thither that the 

 insects turned. Just as gravel, then sand and dust, more and more 

 firmly fill the free spaces between piles of coarse stone, so the hordes 

 of insects, innumerable as sand, small as dust, more and more com- 

 pletely fill the crevices left by the vertebrates. And there are many 

 of these nooks, and the smaller the form the more room there is for it. 



But if what was just said is true, paleontology should confirm it. 

 However delicate, however small the body of the insect, yet under 

 favorable conditions it still left its impression in the thin ooze of 

 the filled basins, and the more than 7,600 species of excavated insects 

 (Handlirsch, 1907) tell us that among them we can seek and should 

 find a confirmation of our thought if it agrees with the truth. 



Insects (evidently) started existence in the lower stratum of the 

 Upper Carboniferous era — i. e., in the middle of the Paleozoic — and 

 already toward the end of that era they have attained considerable 

 development, as shown by the 884 species of insects found there. 



1 Of course, we can not consider the above outlined process of evolution as inevitable for 

 all terrestrial vertebrates. Many departures from it could be found. I aimed to giv" only 

 the general scheme of the process which seemed to me typical for the group of animals 

 under consideration. 



