THE FORMATION OF GERM-CELLS 2O7 



proved, and on what does it depend? It is not based on the 

 animal or vegetable nature of the organisms, for as de Vries 

 himself incidentally acknowledges, we find a similar kind of 

 branching of the primary germ-tracks in the Hydroid-polypes. 

 It simply depends on the fact that a higher i)idividiiaUtv of the 

 stock exists in these animals, just as in the case of the higher 

 plants. In both cases we have to deal not with a single person 

 and the formation of its germ-cells, but with a number of per- 

 sons which arose from the primary one by budding, each of 

 which has a body of its own. and gives rise to its own germ- 

 cells. The germ-track is concealed within the first person of 

 the stock produced from an egg, and gives off a lateral branch 

 as soon as this first polype develops a bud. Shortly afterwards, 

 the polype gives rise to a second bud. into which a lateral germ- 

 track likewise extends ; and when these two buds have developed 

 into complete polypes, they again give rise to buds, into which 

 germ-tracks are once more given off. and so on. The copious 

 branching of the germ-track is thus accounted for, and it is quite 

 immaterial whether the separate persons of the stock are more 

 or less independent and perfect, and to what extent they may be 

 regarded as • individuals.' In those cases in which a periodic 

 segmentation of the body into serially homologous segments or 

 metameres takes place. — each of which has almost a similar 

 origin and is able to produce germ-cells, — the type of the genea- 

 logical tree of the germ-track, as described above, results. 



If. however, we inquire as to the conclusions which can be 

 drawn from the course taken by the germ-tracks in animals and 

 plants, we receive a reply from de Vries which is very significant 

 of the way in which this problem is at present regarded by 

 many botanists : — the whole question which I have raised with 

 regard to the continuity of the gerni-plasin is an idle one. In 

 his opinion, • the whole question as to whether somatoplasm can 

 become transformed into germ-plasm has no basis in fact.' ' A 

 germ-track." says de Vries, ' never arises from a somatic-track,' 

 and -a continuity of the germ-cells exists, not merely in the 

 very rarest cases, but universally and without exception, although 

 it often takes place through a long series by means of the germ- 

 tracks.' 



With the exception of the last one, these sentences merelv 

 repeat my own views, and the apparent contradiction of the latter 

 is simply due to the fact that de Vries adopts expressions which 



