446 THE GERM-PLASM 



Darwin mentions that only thirty per cent, of the seedlings 

 of the wild variegated variety of Ballota iiigra possessed the 

 variegated leaves of the parent-plant ; but sixty per cent, in 

 the second generation were variegated. This is also quite in 

 accordance with our theory ; for the determinants for the leaves 

 in the mother-plant cannot all have been modified, but only the 

 majority ; these would then become diiTerently grouped by means 

 of the reducing divisions of the germ-cells. A seed reproduces 

 either the variety or original form according to whether modified 

 determinants, which were brought together in fertilisation, con- 

 stituted the majority or minority. As in the instance first quoted, 

 variegated plants were alone retained for cultivation in the 

 second generation, and consequently a greater number of the 

 determinants of the variety were brought together at fertilisation : 

 the peixentage of the variety was therefore boiuid to rise in the 

 third generation. This proportion would have increased still 

 further if a fourth and fifth generation had been raised in the 

 same way ; for in those seeds which yield variegated plants 

 the germ-plasm must of necessity contain more modified deter- 

 minants than in the case of those producing the original form. 

 Hence with every generation the chances of an increased 

 majority of modified determinants become greater ; and I have 

 no doubt that in this instance, by the constant selection of the 

 most variegated plants for further cultivation, a ' pure ' variegated 

 race might eventually have been obtained, which would have 

 transmitted its character to the great majority of its offspring — 

 or as we usually express it — 'to all its offspring.' 



The fact that many weeping ashes transmit their special 

 character to many, but not all, the seedlings is also attributable 

 to the diverse effects of the " reducing division ' and amphi- 

 mixis, the former of which causes the introduction into the 

 germ-plasm of a large majority of modified determinants, and 

 the latter of only a slight one. The manner in which the 

 variety arises must here, however, be taken into account. Btid- 

 variatiotis are ?nnch more rarely reproduced by seeds than are 

 variations arisiftg from seeds; but, on the other hand, they can 

 almost always be propagated by grafting, budding, or by cuttings. 

 Hence the capacity of a certain individual for transmitting the 

 variation to its seeds may be owing to its having arisen from 

 a seed, while in another case the same variation arose in a bud, 

 and it could therefore rarely or never be transmitted by seeds. 



