THE GERM-PLASM THEOEY 405 



of as disposed in a manifold overlapping series. That they do not 

 enter into activity all at once, but successively take their part in 

 development, seems to me a necessary consequence of their successive 

 origin in the phylogeny; and the ontogeny, as we shall see later, 

 arises through a modified condensation of the phylogeny. Now since 

 every new determinant that arises in the course of phylogeny can 

 only develop by division and subsequent variation from the deter- 

 minants which were previously active at the same place in the 

 organism, it is quite intelligible that later on, when the phylogeny 

 has been condensed in the ontogeny, they should not enter upon their 

 active stage at the same time as their phyletic predecessors, but after 

 them. The theory of Oscar Hertwig, who starts from a germ-plasm 

 without primary constituents, that all parts of the germ-plasm become 

 active at the same time, seems to me quite untenable. How could the 

 wheels, levers, and springs of the complete vital machine, which arose 

 so very slowly in the course of phylogeny, arise to-day in the ontogeny 

 in such rapid succession unless they were already present in the 

 germ-plasm and only required to be incited to activity, that is, 

 liberated by the stage preceding them ? Even Fechner supported this 

 view when he supposed that the interaction and mutual influences of 

 the parts in the organism, that is, of the ' constellations,' gave rise of 

 themselves to the succeeding stage, that is to say, to the new constella- 

 tions peculiar to the succeeding stage. To this Reinke reasonably 

 objected that it was like expecting the window frames of a house in 

 process of building to produce the panes of glass. The panes in the 

 organism only develop in the window frames if their determinants 

 have been present in the germ-plasm from the beginning, and are 

 liberated by the development of the frames, just as the activity of the 

 glazier is liberated by the sight of the completed frames. Neither 

 new panes nor new determinants could be produced rapidly; the 

 former must be manufactured in the glass factory, the latter in the 

 developmental workshop of the form of life in question, which 

 workshop we call its phylogeny. But just as it is unnecessary to 

 erect a new glass factory for each new house that is built, so the 

 development of each individual does not require the establishment 

 each time of those numberless life-factories— the constellations — 

 whose business it is to produce anew the wheels, levers, springs, and 

 cylinders of the developmental machinery at each stage, for they 

 are all provided for in the germ-plasm, and it is only on this account 

 that they are capable of hereditary variation. 



I have already directed attention to some embryological facts 

 which seem to be contradictory, if not to the germ-plasm theory itself , 



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