MULTIPLICATION P,Y GEMMATION 1 63 



of the mother-animal which passes into the buds, practical! v 

 corresponds only to the future sexual apparatus.' This, however, 

 can merely be taken as an explanation of the fact in so far as it 

 indicates the possibility of the ' mesoderm cells ' of the stolon 

 and bud containing the groups of determinants required for these 

 different structures. For all the determinants must be present 

 in the sexual cells, and, owing to their disintegration during cell- 

 division, they may become arranged in very varied groups, so 

 that certain mesoderm cells may become furnished with one 

 group and others with another. This certainly presupposes 

 that the process of the distribution of the determinants in this 

 case is entirely different from that w^hich takes place during 

 embryogen}', and this difference, again, can only depend on 

 a difference in the original architecture of the idioplasm. In 

 discussing the process of alternation of generations I shall 

 once more return to this point, which, from a theoretical point 

 of view, is a very fundamental one. 



2. The Process of Gemmation in Plants 



Our conception of the process of gemmation has been in the 

 first instance derived from the vegetable kingdom : all the higher 

 plants correspond to stocks or corms which arise by copious and 

 regular budding, much as occurs in the case of such animal- 

 stocks as those of the Hydrozoa, for instance. Although the 

 physiological individuality of separate ' persons ' in a plant is 

 often less defined than in the case of many animal colonies, there 

 can nevertheless be no doubt as to the morphological value of a 

 shoot as a 'person,' in the sense in which Haeckel uses the term. 



Although as regards animal colonies, it has not yet in all 

 instances been possible to ascertain with absolute certainty the 

 actual origin of the processes of budding in connection with the 

 cell-generations of the first person of the colony, this has been 

 done very accurately in the case of plants ; a theory of heredity 

 can therefore be much more safely applied to the process of 

 gemmation in plants than to that in animals. 



In many i)lants, at any rate, budding originates from a si>ii!:;le 

 cell, situated at the apex of the growing shoot, and known as the 

 ' apical cell.' This cell grows and undergoes a series of divisions, 

 much as occurs in the development of the ovum, and thus gives 

 rise to a group of cells, the number, form, and arrangement of 



