Page:Insects - Their Ways and Means of Living.djvu/109

 ==CHAPTER III==

ROACHES AND OTHER ANCIENT INSECTS
We used to speak quite confidently of time as something definite, measurable by the clock, and of a year or a century as specific quantities of duration. In this present age of relativity, however, we do not feel so certain about these things. Geologists calculate in years the probable age of the earth, and the length of time that has elapsed since certain events took place upon it, but their figures mean only that the earth has gone around the sun approximately so many rimes during the interval. In biology it signifies nothing that one animal has been on the earth for a million years, and another for a hundred million, for the unit of evolution is not a year, but a generation. If one animal, such as most insects, has from one to many generations every year, and another, such as man, has only four or rive in a century, it is evident that the first, by evolutionary reckoning, will be vastly older than the second, even though the two have made the same number of trips with the earth around the sun. An insect that antedates man by several hundred million years, therefore, is ancient indeed. The roach scarcely needs an introduction, being quite well known to all classes of society in every inhabited part of the world. That he has long been established in human communities is shown by the fact that the various nations have bestowed different names upon him. His common English name of "cockroach" is said to come from the Spanish, cucaracha. The Germans call him, rather disrespectfully, Küchenschabe, which signifies "kitchen [77]