Part 7 (1/2)

I may be a dreamer: and I may consider, in my turn, as wilder dreamers than myself, certain persons who fancy that their only business in life is to make money, the scientific man's only business is to show them how to make money, and the soldier's only business to guard their money for them. Be that as it may, the finest type of civilised man which we are likely to see for some generations to come, will be produced by a combination of the truly military with the truly scientific man. I say--I may be a dreamer: but you at least, as well as my scientific friends, will bear with me; for my dream is to your honour.

ON BIO-GEOLOGY.

AN ADDRESS GIVEN TO THE SCIENTIFIC SOCIETY OF WINCHESTER.

I am not sure that the subject of my address is rightly chosen. I am not sure that I ought not to have postponed a question of mere natural history, to speak to you, as scientific men, on the questions of life and death, which have been forced upon us by the awful warning of an ill.u.s.trious personage's illness; of preventible disease, its frightful prevalency; of the 200,000 persons who are said to have died of fever alone since the Prince Consort's death, ten years ago; of the remedies; of drainage; of sewage disinfection and utilisation; and of the a.s.sistance which you, as a body of scientific men, can give to any effort towards saving the lives and health of our fellow-citizens from those unseen poisons which lurk like wild beasts couched in the jungle, ready to spring at any moment on the unsuspecting, the innocent, the helpless.

Of all this I longed to speak: but I thought it best only to hint at it, and leave the question to your common sense and your humanity; taking for granted that your minds, like the minds of all right-minded Englishmen, have been of late painfully awakened to its importance. It seemed to me almost an impertinence to say more in a city of whose local circ.u.mstances I know little or nothing. As an old sanitary reformer, practical, as well as theoretical, I am but too well aware of the difficulties which beset any complete scheme of drainage, especially in an ancient city like this; where men are paying the penalty of their predecessors' ignorance; and dwelling, whether they choose or not, over fifteen centuries of acc.u.mulated dirt.

And, therefore, taking for granted that there is energy and intellect enough in Winchester to conquer these difficulties in due time, I go on to ask you to consider, for a time, a subject which is growing more and more important and interesting, a subject the study of which will do much towards raising the field naturalist from a mere collector of specimens--as he was twenty years ago--to a philosopher elucidating some of the grandest problems. I mean the infant science of Bio-geology--the science which treats of the distribution of plants and animals over the globe, and the causes of that distribution.

I doubt not that there are many here who know far more about the subject than I; who are far better read than I am in the works of Forbes, Darwin, Wallace, Hooker, Moritz Wagner, and the other ill.u.s.trious men who have written on it. But I may, perhaps, give a few hints which will be of use to the younger members of this Society, and will point out to them how to get a new relish for the pursuit of field science.

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 cla.s.sifier'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 here? 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 cla.s.s. Madam Nature allows no dangerous cla.s.ses, 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 landloupers, 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 fas.h.i.+on.

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-sh.o.r.e, 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 gra.s.ses 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 const.i.tuents in our woody fibre; again, because we want a certain amount of moisture at a certain period of the year: or, perhaps, simply because the mechanical arrangement of the particles of a certain soil happens to suit the shape of our roots and of their stomata. Sometimes you will get an answer quickly enough; sometimes not. If you ask, for instance, _Asplenium viride_ how it contrives to grow plentifully in the Craven of Yorks.h.i.+re down to 600 or 800 feet above the sea, while in Snowdon it dislikes growing lower than 2000 feet, and is not plentiful even there?--it will reply--Because in the Craven I can get as much carbonic acid as I want from the decomposing limestone: while on the Snowdon Silurian I get very little; and I have to make it up by clinging to the mountain tops, for the sake of the greater rainfall. But if you ask _Polopodium calcareum_--How is it you choose only to grow on limestone, while _Polypodium Dryopteris_, of which, I suspect, you are only a variety, is ready to grow anywhere?--_Polypodium calcareum_ will refuse, as yet, to answer a word.

Again--I can only give you the merest string of hints--you will find in your questionings that many plants and animals have no reason at all to show why they should be in one place and not in another, save the very sound reason for the latter which was suggested to me once by a great naturalist. I was asking--Why don't I find such and such a species in my parish, while it is plentiful a few miles off in exactly the same soil?--and he answered--For the same reason that you are not in America.

Because you have not got there. Which answer threw to me a flood of light on this whole science. Things are often where they are, simply because they happen to have got there, and not elsewhere. But they must have got there by some means: and those means I want young naturalists to discover; at least to guess at.

A species, for instance--and I suspect it is a common case with insects--may abound in a single spot, simply because, long years ago, a single brood of eggs happened to hatch at a time when eggs of other species, who would have competed against them for food, did not hatch; and they may remain confined to that spot, though there is plenty of good food for them outside it, simply because they do not increase fast enough to require to spread out in search of more food. Thus I should explain a case which I heard of lately of _Anthocera trifolii_, abundant for years in one corner of a certain field, and only there; while there was just as much trefoil all round for its larvae as there was in the selected spot.

I can, I say, only give hints: but they will suffice, I hope, to show the path of thought into which I want young naturalists to turn their minds.

Or, again, you will have to inquire whether the species has not been prevented from spreading by some natural barrier. Mr. Wallace, whom you all of course know, has shown in his 'Malay Archipelago' that a strait of deep sea can act as such a barrier between species. Moritz Wagner has shown that, in the case of insects, a moderately broad river may divide two closely allied species of beetles, or a very narrow snow-range two closely allied species of moths.

Again, another cause, and a most common one is: that the plants cannot spread because they find the ground beyond them already occupied by other plants, who will not tolerate a fresh mouth, having only just enough to feed themselves. Take the case of _Saxifraga hypnoides_ and _S.

umbrosa_, ”London pride.” They are two especially strong species. They show that, _S. hypnoides_ especially, by their power of sporting, of diverging into varieties; they show it equally by their power of thriving anywhere, if they can only get there. They will both grow in my sandy garden, under a rainfall of only 23 inches, more luxuriantly than in their native mountains under a rainfall of 50 or 60 inches. Then how is it that _S. hypnoides_ cannot get down off the mountains; and that _S.

umbrosa_, though in Kerry it has got off the mountains and down to the sea level, exterminating, I suspect, many species in its progress, yet cannot get across county Cork? The only answer is, I believe: that both species are continually trying to go ahead; but that the other plants already in front of them are too strong for them, and ma.s.sacre their infants as soon as born.

And this brings us to another curious question: the sudden and abundant appearance of plants, like the foxglove and _Epilobium angustifolium_, in spots where they have never been seen before. Are their seeds, as some think, dormant in the ground; or are the seeds which have germinated fresh ones wafted thither by wind or otherwise, and only able to germinate in that one spot, because there the soil is clear? General Monro, now famous for his unequalled memoir on the bamboos, holds to the latter theory. He pointed out to me that the _Epilobium_ seeds, being feathered, could travel with the wind; that the plant always made its appearance first on new banks, landslips, clearings, where it had nothing to compete against; and that the foxglove did the same. True, and most painfully true, in the case of thistles and groundsels: but foxglove seeds, though minute, would hardly be carried by the wind any more than those of the white clover, which comes up so abundantly in drained fens.

Adhuc sub judice lis est, and I wish some young naturalists would work carefully at the solution; by experiment, which is the most sure way to find out anything.

But in researches in this direction they will find puzzles enough. I will give them one which I shall be most thankful to hear they have solved within the next seven years--How is it that we find certain plants, namely, the thrift and the scurvy gra.s.s, abundant on the sea-sh.o.r.e and common on certain mountain-tops, but nowhere between the two? Answer me that. For I have looked at the fact for years--before, behind, sideways, upside down, and inside out--and I cannot understand it.

But all these questions, and specially, I suspect, that last one, ought to lead the young student up to the great and complex question--How were these islands re-peopled with plants and animals, after the long and wholesale catastrophe of the glacial epoch?

I presume you all know, and will agree, that the whole of these islands, north of the Thames, save certain ice-clad mountain-tops, were buried for long ages under an icy sea. From whence did vegetable and animal life crawl back to the land, as it rose again; and cover its mantle of glacial drift with fresh life and verdure?

Now let me give you a few prolegomena on this matter. You must study the plants of course, species by species. Take Watson's 'Cybele Britannica,'

and Moore's 'Cybele Hibernica;' and let--as Mr. Matthew Arnold would say--”your thought play freely about them.” Look carefully, too, in the case of each species, at the note on its distribution, which you will find appended in Bentham's 'Handbook,' and in Hooker's 'Student's Flora.'

Get all the help you can, if you wish to work the subject out, from foreign botanists, both European and American; and I think that, on the whole, you will come to some such theory as this for a general starting platform. We do not owe our flora--I must keep to the flora just now--to so many different regions, or types, as Mr. Watson conceives, but to three, namely: an European or Germanic flora, from the south-east; an Atlantic flora, from the south-west; a Northern flora from the north.

These three invaded us after the glacial epoch; and our general flora is their result.