OCR Text |
Show 20 TilE PRESENT CONDITION the divm·sity of the physiological functions which are exerted by each. If I were to take an oak tree as a specimen of the plant world; I should find that it originated in a~ acorn, which, too, commenced in a cell;. the ac.orn IS placed in the ground, and it very speedily begins to absorb the inorganic matters I have named, adds enormously to its bulk, and we can see it, year after year, extending itself upward and downward, attr~cting and appropriating to itself inorganic materials, which it vivifies, and eventually, as it ripens, gives off its o\fn proper acorns, which again run the same course. But I need not multiply examples,-from the hio·hest to the lowest the essential features of life are 0 the same, as I have described in each of these cases. So much, then, for these particular features of the organic world, which you can understand and comprehend, so long as you confine yourself to one sort of living being, and study that only. But, as you know, horses are not the only living creatures in the world ; and again, horses, like all other animals, have certain limits-are confined to a certain area on the surface of the earth on which we live,-and, as that is the simpler matter, I may take that first. In its wild state, and before the discovery of America, when the natural state of things was interfered with by the Spaniards, the Horse was only to be found in parts of the earth which are known to geographers as the Old World; that is to say, you might meet with horses in Europe, Asia, or Africa; but there were none in Australia, and there were none whatsoever in the whole continent of America, from OF ORGANIC NATURE. 21 Labrador down to Cape I-Iorn. rrhis 1s an empirical fact, and it is what is called, stated in the way I have given it you, the (Geographical Distribution' of the Horse. Why horses should be found in Europe, Asia, and Africa, and not in America, is not obvious; the explanation that the conditions of life in America are unfavourable to their existence, and that, therefore, they had not been created there, evidently does not apply; for when the invading Spaniards; or our own yeomen farmers, conyeyed horses to these countries for their own use, they were found to thrive well and multiply very rapidly; and many are even now running wild in those countries, and in a perfectly natural condition. Now, suppose we were to do for every animal what we have here done for the Horse,- that is, to mark off and distinguish the particular district or region to which each belonged; and supposing we tabulated all these results, that would be called the Geographical Distribution of animals) while a corresponding study of plants would yield as a result the Geographical Distribution of plants. I pass on from that now, as I merely wished to explain to you what I meant by the use of the term 'Geographical Distribution.' As I said, there is another aspect, and a 1nuch more important oneJ and that is) the relations of the various animals to one another. The Horse is a very well-defined matter-offact sort of anilnal, and we are all pretty familiar with its structure. I dare say it may have struck you, that it resembles very much no other member of the animal kingdom, except perhaps the Zebra or the Ass. |