62 POPULAR SCIENCE MONTHLY 



Protorthoptera, ancestors of the Orthoptera, or locusts, etc. Nearly all 

 these insects attained a considerable size; indeed, there were many the 

 span of whose wings measured much more than half a meter — they 

 were literally giants ! 



These forms, too, decrease in number, and at last there appears to 

 us a quite distinct fauna of primitive creatures, whose structure was 

 of the simplest order, and who were apparently without adaptation to 

 the definite modes of life which we are accustomed to see in nearly all 

 existing insects. These primitive forms we call ' Palseodictyoptera,' 

 and among them it is possible to distinguish a series of different genera 

 and species, all, however, having common characters and standing in 

 about the same degree of relationship to existing groups. 



These palaeodictyopteres, therefore, constitute the first shoot of the 

 giant tree which we have to-day in the insect world. 



As has been frequently indicated, we also see that the race of in- 

 sects has by no means remained unaltered since primitive times, but 

 that it has been subjected to precisely the same changes as have other 

 groups of animals. And the conclusions to be drawn from these 

 mutations are manifold. In the first place, they permit us to erect 

 a natural system in accordance with actual descent; they permit us to 

 weigh the characters accurately and to distinguish between those which 

 are old and inherited and those that are recent and acquired. More- 

 over, they afford us many and far-reaching conclusions regarding the 

 climate and the nature of the soil in those times and regions, as well 

 as the distribution of land and water, etc. Finally, by this means 

 we are also enabled to penetrate a very little into the future. And 

 this further shows us that eventually neither the boy with the green 

 net nor the imprecating pessimist will be so very far wrong, for the 

 immediate future probably belongs to the brilliantly colored insects, on 

 the one hand, and, on the other, to the troublesome and offensive 

 vermin, the parasites of man, animals and plants. These two extremes 

 appear to us to-day in their greatest development. 



