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17 acquired variations are not themselves inherited they play an indirect part in the origin of species in as much as they act as a shield favouring the origin and growth of such congenital variations as are appropriate to the habit. It has been suggested that we may find in this so-called "organic selection" an explanation of the origin of co-ordinated Structures which has proved such a stumbling block to those who like Weismann believe in the "all-sufficiency" of natural selection. It makes it possible for us to understand how intelligence might become a factor in evolution. Intelligence often leads to the formation of new habits and thus to the development of acquired character. Any congenital variations which coincided in description with the modifications thus produced would be favoured and eventually preserved.

But it must not be supposed that biologists are yet agreed in throwing over the Lamarckian factors and in denying their transmissibility. The question is still an open one. It is true that many of the arguments generally adduced in favour of the inheritance of acquired characters have been found inconclusive, but some facts still remain which are difficult to explain without the help of such factors. The decision of the question is rendered very difficult owing to the fact that in the case of wild animals and plants it is almost impossible often to exclude the of natural selection having