466 THE GERM-PLASM 



plasm and the • reserve germ-plasm ' — destined to form germ- 

 cells — following different courses, and consequently they will not 

 always contain the same number of modified ids. The in- 

 frequency of the transmission of bud-variations by seeds may 

 depend on the production of a new combination of ids of the 

 ' reserve germ-plasm ' from which the germ-cells are formed, 

 whenever this formation occurs, owing to the ' reducing divi- 

 sion ' and amphimixis. No such occurrence takes place in 

 the ^ blastogenic' germ-plasm as long as merely asexual repro- 

 duction continues. 



According to our view, the power of transmission — which is 

 possessed by all organisms, and on which the development of 

 the higher organic forms is based — therefore depends on simple 

 growth merely in the case of the very lowest conceivable 

 organisms with which we are not acquainted ; while in all forms 

 which have already undergone differentiation, it results from 

 the possession of a special appa7-atiis for U'aiisinissioji. 



This apparatus first occurs in the unicellular organisms, in 

 which it consists of a substance composed of the different kinds 

 of vital units or biophors, which occur in the substance of the 

 organism, and presumably in a similar proportion ; there are, 

 at any rate, numerous individual biophors of every kind, all of 

 which are arranged together on a definite plan. This substance 

 is surrounded by a membrane, — the nuclear membrane, — pro- 

 vided with pores, through which the biophors of the nucleus 

 can pass into the cell-body, there to multiply at the expense 

 of the nutritive materials — to which the vital particles of the 

 cell-body themselves may become reduced under certain cir- 

 cumstances — and to become arranged in virtue of the forces 

 dwelling within them. 



To these processes is due the power possessed by the 

 organism of giving rise by division to two complete individuals 

 of a similar nature. 



Even at this stage of differentiation, the hereditary substance 

 is rendered more complicated by the process of amphimixis, 

 or mingling of individual differences, in which this substance 

 periodically becomes halved, and is then again completed by the 

 hereditary substance of another individual. The result is, that 

 every part of the organism is represented in the hereditary 

 substance by different varieties of the same kind of biophor. 



