Weismanns theory of Evolution (1891). 95 



and by other buds from that shoot, but sometimes 

 also by seeds wb'^h the flowers of the shoot sub- 

 sequently produce — in which case all the laws 

 of inheritance that apply to congenital variations 

 are found to apply also to bud-variation. Or, as 

 Darwin puts it, " there is not any particular in which 

 new characters arising by bud-variation can be dis- 

 tinguished from those due to seminal variation " ; 

 and, therefore, any theory which deals with the latter 

 is bound also to take cognizance of the former. Now, 

 as far as I can find, there is only one paragraph in 

 which Weismann alludes to bud-variation, and what 

 he there says I do not find very easy to understand. 

 Therefore I will quote the whole paragraph verbatim. 



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 un- 

 changed germ-plasm of the first ontogenetic stage, but of this 

 substance altered, so far as to correspond with the altered 

 structure of the individual which arises from it — viz., the root- 

 less 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 depend chiefly on 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 idio-plasm [? of that 

 particular bud], when it develops into a flowering shoot, produces 

 at the same time the germ-celis which are found in the latter. 

 We thus approach an understanding of Fritz M filler's obser- 

 vation ; for if the whole shoot which produces the flower arises 

 from the same idio-plasm which also forms its germ-cells, we can 

 readily understand why the latter should contain the same 

 hereditary tendencies which were previously expressed in the 

 flower which produced them. The fact that variations may 



