322 THE SIGNIFICANCE OP SEXUAL REPRODUCTION 



If, however, acquired characters are brought forward in con- 

 nexion with the question of the transformation of species, the term 

 ' acquired ' must only be applied to those characters which do not 

 arise from within the organism, but which arise as the reaction of 

 the organism under some external stimulus, most commonly as the 

 consequence of the increased or diminished use of an organ or part. 

 We have then to learn whether the altered conditions of life, by 

 forcing an organism to adopt new habits, can by such means lead 

 directly, and not indirectly through natural selection, to the 

 transformation of the species ; or whether the effects of increased 

 or diminished use of certain parts, implied by the new habits, are 

 restricted to the individual itself, and therefore powerless to effect 

 any direct modification of the species. 



Fritz Miiller's observation is also interesting in another re- 

 spect : it appears to controvert my views upon heredity as expressed 

 in the theory of the continuity of the germ-plasm. If a single 

 flower can transmit to its descendants special peculiarities which 

 were not possessed by its ancestors, we seem to be driven to the 

 conclusion that the ancestral germ-plasm has not passed into the 

 flower in question, but that new germ-plasm has been formed, 

 inasmuch as the new characters are derived from the flower itself, 

 and not from any of its ancestors. I think, however, that the 

 observation admits of another interpretation : a specimen of Abu- 

 tilon with many hundred flowers is not a single individual, but a 

 colony consisting of numerous individuals which have arisen by 

 budding from the first individual developed from the seed. 



I have not hitherto considered budding in relation to my 

 theories, but it is obvious that it is to be explained from my point 

 of view, by supposing that the germ-plasm which passes on into a 

 budding individual consists not only of the unchanged idioplasm of 

 the first ontogenetic stage (germ-plasm), but of this substance altered, 

 so far as to correspond with the altered structure of the individual 

 which arises from it viz. the rootless shoot which springs from the 

 stem or branches. The alteration must be veiy slight, and perhaps 

 quite insignificant, for it is possible that the differences between the 

 secondary shoots and the primary plant may chiefly depend upon 

 the changed conditions of development, which takes place beneath 

 the earth in the latter case, and in the tissues of the plant in 

 the former. Thus we may imagine that the idioplasm, when it 



