FOSSIL INSECTS 57 



or half wings, are counted, the round sum of 360,000 species of insects 

 now known is reached. 



Estimates have been given showing that not more than one sixth 

 of all forms actually existing have as yet been described and named, 

 so that the number of species (not individuals) now living in the 

 present period of the earth's history may be placed at about 2,000,000. 



It is quite conceivable that man in his effort to understand nature 

 everywhere surrounding him should not be satisfied merely to study all 

 these existing insects and arrange them in a system of orders, families, 

 genera, etc., but he would also wish to know how this greatest division 

 of the animal kingdom, in specific numbers about doubly exceeding 

 all other groups, has been developed, and how and when it has attained 

 its present size. 



If we would really learn the primitive history of the insect tribe, 

 and not construct it in a speculative manner, we must descend into 

 the depths of the earth in order to see whether or not a fortunate 

 chance has possibly preserved some remains which might afford us an 

 insight into the insect life of previous ages. 



If, as mentioned above, the number of various species of insects 

 now existing be taken in round numbers at 2,000,000, and for each 

 species at least 1,000,000,000 individuals yearly, which, judging from 

 the swarms of bees and gnats, colonies of ants and termites, parasites 

 of plants (often millions living on a single tree), certainly seems 

 legitimate, an annual total of 2,000,000,000,000,000 (two thousand 

 trillions) individuals is obtained, while during the time that man has 

 inhabited the earth some hundreds of trillions must have existed. 



And of all these trillions of insect remains, which moderately com- 

 puted (about 100 to a gram) represent 1,000 billion kilograms in 

 weight, we have as yet found but a few hundred examples, and these 

 have been accidentally enclosed in gum (copal), in peat-beds, or 

 finally buried in hardened mud. They have thus become more or less 

 well preserved, and again by chance have fallen into our hands. All 

 these forms clearly demonstrate that the species of insects have not 

 materially altered during man's sojourn on the earth. 



It may now be concluded that these results must lead only to dis- 

 couragement, for they show very plainly how small a percentage of the 

 insect world escapes complete destruction, and how slight is the pros- 

 pect of securing any of these remains. 



Notwithstanding this, it has already come to pass that quite a num- 

 ber of fossil insects have been brought to light from analogous deposits 

 of older periods, and the explanation may be partly found in the fact 

 that even these older strata are to be estimated not only by thousands, 

 but probably by millions of years, so that the sum total of vanished 

 and preserved forms must evidently increase accordingly. 



