Seite - 138 - in The Origin of Species

138 ORIGIN OF SPECIES Finally, I believe that many lowly organised forms now exist throughout the world, from various causes. In some cases variations or individual differences of a favorable na- ture may never have arisen for natural selection to act on and accumulate. In no case, probably, has time sufficed for the utmost possible amount of development. In some few cases there has been what we must call retrogression of organisa- tion. But the main cause lies in the fact that under very simple conditions of life a high organisation would be of no service,—possibly would be of actual disservice, as being of a more delicate nature, and more liable to be put out of order and injured. Looking to the first dawn of life, when all organic beings, as we may believe, presented the simplest structure, how, it has been asked, could the first steps in the advancement or differentiation of parts have arisen? Mr. Herbert Spencer would probably answer that, as soon as simple unicellular organism came by growth or division to be compounded of several cells, or became attached to any supporting surface, his law "that homologous units of any order became differ- entiated in proportion as their relations to incident forces became different" would come into action. But as we have no facts to guide us, speculation on the subject is almost use- less. It is, however, an error to suppose that there would be no struggle for existence, and, consequently, no natural selection, until many forms had been produced: variations in a single species inhabiting an isolated station might be beneficial, and thus the whole mass of individuals might be modified, or two distinct forms might arise. But, as I re- marked towards the close of the Introduction, no one ought to feel surprise at much remaining as yet unexplained on the origin of species, if we make due allowance for our pro- found ignorance on the mutual relations of the inhabitants of the world at the present time, and still more so during past ages. CONVERGENCE OF CHARACTER Mr. H. C. Watson thinks that I have overrated the im- portance of divergence of character (in which, however, he apparently believes), and that convergence, as it may be