[Footnote 32: _Journ. Roy. Micro. Soc._ 1887, President’s Address.] A study of the Desmids, the Diatoms, the Radiolaria, or the Foraminifera amongst minute organisms will show that variations are so constant and so numerous, that the determination of what is called species, is difficult, and at times, impossible. Who does not know of the varieties that are annually produced from seed-growths of favourite flowering plants?—the pelargonium, the primula, the viola, the rose, and hundreds of others. That this is not confined to forms under cultivation is equally manifest. Common observation has not noted it perhaps, but there are no fewer than thirteen distinct forms of the common bramble or blackberry, with stem, flower, and fruit sufficiently varied to have induced some botanists to consider them species. Although each when seen is called by the majority of people ‘the wild rose,’ there are at the very least seventeen natural varieties. ‘Artificial selection’ has had no part in these variations and a thousand others that might be named. Consider the variations constantly arising in fowls, canaries, dogs, and cattle. No litter of kittens is ever precisely alike, or precisely like either parent; and this is true even in human families. Variation, then, is constant and universal; it acts in all directions and in every living thing. If, amidst the exigencies of the history of an organism, some variation in the progeny is beneficial in altered circumstances, it is by the very nature of things preserved. The offspring of all living organisms are greatly in excess of the number that can reach maturity; and with variations in every organism, and in every part of their organization, for ever occurring; and environments, during great cycles of time, undergoing constant and enormous changes; it is palpable that successive modifications must arise, and through all the countless ages of the past have arisen: resulting always in the ‘survival of the fittest’ or ‘natural selection,’ which ‘signifies the preservation of favourable individual differences and variations, and the destruction of those which are injurious.’[33] This is palpable, for individuals possessed of advantage over others must have the best chance of surviving and multiplying their kind; hence arise ‘varieties,’ ‘races,’ and ‘species;’ and if the enormous age of the period of life upon the globe, and the vicissitudes through which it has passed, be taken into account, it is impossible for a biologist to withhold consent to the fact that a ‘law,’ a method, has been demonstrated, which has been a certain and powerful factor, in producing the variety of the flora and fauna that have filled the earth, from the dawn of life upon the globe, up to the extant animals and vegetables which are the latest outcome of this great law. This is the conviction of all the experts of the world. [Footnote 33: Darwin’s _Origin of Species_, 6th ed. p. 63.]