CHARLES DARWIN 239 



throughout the world, from various causes. In some cases variations 

 or individual differences of a favourable nature 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 

 organisation. 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 of 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 become differ- 

 entiated in proportion as their relations to incident forces become 

 different" would come into action. But as we have no facts to guide 

 us, speculation on the subject is almost useless. 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 pro- 

 duced; 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 remarked to- 

 wards 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 profound ignorance on the mutual rela- 

 tions 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 importance 

 of divergence of character (in which, however, he apparently be- 

 lieves), and that convergence, as it may be called, has likewise played 

 a part. If two species, belonging to two distinct though allied genera, 

 had both produced a large number of new and divergent forms, it 

 is conceivable that these might approach each other so closely that 

 they would have all to be classed under the same genus ; and thus the 



