Bio-geology, then, begins with asking every plant or animal you meet, large or small, not merely—­What is your name?  That is the collector and classifier’s duty; and a most necessary duty it is, and one to be performed with the most conscientious patience and accuracy, so that a sound foundation may be built for future speculations.  But young naturalists should act not merely as Nature’s registrars and census-takers, but as her policemen and gamekeepers; and ask everything they meet—­How did you get there?  By what road did you come?  What was your last place of abode?  And now you are here, how do you get your living?  Are you and your children thriving, like decent people who can take care of themselves, or growing pauperised and degraded, and dying out?  Not that we have a fear of your becoming a dangerous class.  Madame Nature allows no dangerous classes, in the modern sense.  She has, doubtless for some wise reason, no mercy for the weak.  She rewards each organism according to its works; and if anything grows too weak or stupid to take care of itself, she gives it its due deserts by letting it die and disappear.  So, you plant or you animal, are you among the strong, the successful, the multiplying, the colonising?  Or are you among the weak, the failing, the dwindling, the doomed?

These questions may seem somewhat rude:  but you may comfort yourself by the thought that plants and animals, though they deserve all kindness, all admiration, deserve no courtesy—­at least in this respect.  For they are, one and all, wherever you find them, vagrants and landlopers, intruders and conquerors, who have got where they happen to be simply by the law of the strongest—­ generally not without a little robbery and murder.  They have no right save that of possession; the same by which the puffin turns out the old rabbits, eats the young ones, and then lays her eggs in the rabbit-burrow—­simply because she can.

Now, you will see at once that such a course of questioning will call out a great many curious and interesting answers, if you can only get the things to tell you their story; as you always may if you will cross-examine them long enough; and will lead you into many subjects beside mere botany or entomology.  So various, indeed, are the subjects which you will thus start, that I can only hint at them now in the most cursory fashion.

At the outset you will soon find yourself involved in chemical and meteorological questions; as, for instance, when you ask—­How is it that I find one flora on the sea-shore, another on the sandstone, another on the chalk, and another on the peat-making gravelly strata?  The usual answer would be, I presume—­if we could work it out by twenty years’ experiment, such as Mr. Lawes, of Rothampsted, has been making on the growth of grasses and leguminous plants in different soils and under different manures—­the usual answer, I say, would be—­Because we plants want such and such mineral constituents in