v.] IN THE THEORY OF NATURAL SELECTION 33 1 



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 indirectlj?^ 

 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 eifect 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 pecu- 

 liarities 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 flov/er 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 inter- 

 pretation : a specimen of Abiitilon with many hundred flowers 

 is not a single individual, but a colony consisting of numerous 

 individuals which have arisen by budding from the first indi- 

 vidual 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 ni}^ 

 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 very 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 con- 

 ditions 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 developes 

 into a flowering shoot, produces at the same time the germ-cells 

 which are found in the latter. We thus approach an under- 

 standing of Fritz Mailer's observation ; for if the whole shoot 



