438 Conclusion and summaey Chap, xl 



also seen that in the case of plants the male element may 

 affect in a direct manner the tissues of the mother, and 

 with animals may lead to the modification of her future pro- 

 geny. In the vegetable kingdom the offspring from a cross 

 between two species or varieties, whether effected by seminal 

 generation or by grafting, often revert, to a greater or less 

 degree, in the first or in a succeeding generation, to the two 

 parent-forms ; and this reversion may affect the whole flower, 

 fruit, or leaf-bud, or only the half or a smaller segment of a 

 single organ. In some cases, however, such segregation of 

 character apparently depends on an incapacity for union rather 

 than on reversion, for the flowers or fruit which are first pro- 

 duced display by segments the characters of both parents. The 

 various facts here given ought to be well considered by any 

 one who wishes to embrace under a single point of view the 

 man}^ modes of reproduction by gemmation, division, and 

 sexual union, the reparation of lost parts, variation, inheritance, 

 reversion, and other such phenomena. Towards the close of 

 the second volume I shall attempt to connect these facts 

 together by the hypothesis of pangenesis. 



In the early half of the present chapter I have given a long 

 list of plants in which through bud-variation, that is, inde- 

 pendently of reproduction by seed, the fruit has suddenly 

 become modified in size, colour, flavour, hairiness, shape, and 

 time of maturity ; flowers have similarly changed in shape, 

 colour, in being double, and greatly in the character of the 

 calyx ; young branches or shoots have changed in colour, in 

 bearing spines and in habit of growth, as in climbing or in 

 weeping ; leaves have changed in becoming variegated, in 

 shape, period of unfolding, and in their arrangement on the 

 axis. Buds of all kinds, whether produced on ordinary branches 

 or on subterranean stems, whether simple or much modified 

 and supplied with a stock of nutriment, as in tubers and bulbs, 

 are all liable to sudden variations of the same general nature. 



In the list, many of the cases are certainly due to reversion 

 to characters not acquired from a cross, but which were 

 formerly present and have since been lost for a longer or 

 shorter time ; — as when a bud on a variegated plant produces 

 plain leaves, or when the variously-coloured flowers of the 



