82 Hypothesis of Structure of Germ Substance 



little discs of chromatin of the chromatic filament, in 

 exactly the same disposition as that which these little 

 discs actually do present in the chromatic filament. 



Admitting then that nuclear division is always quali- 

 tatively equal we must now ask: does this really mean 

 that the nuclei of all cells must remain alike throughout 

 the whole of development? 



But before taking up this question we must first 

 answer a preliminary one : must we exclude nuclear som- 

 atization with the epigenesists or admit it with the pre- 

 formists ? 



If it seemed to us impossible to disagree with the 

 epigenesists upon the first question of a qualitatively equal 

 nuclear division, it seems on the contrary impossible to 

 disagree with the preformists on this second of a nuclear 

 somatization. We shall certainly not repeat here all the 

 arguments by which these latter support their thesis. 

 They can be summed up in their essential parts in the 

 following words of Weismann. 



"The chromatin is able to imprint upon the cell in 

 the nucleus of which it lies a specific character. Just as 

 the thousands of cells which make up the organism 

 possess very different characters and very different 

 functions, so the chromatin which controls them cannot 

 be every where alike, but must rather be different in 

 different kinds of cells." 52 



The epigenesists, on the contrary, are well known 

 to be inclined to the view that all the somatic cells of 

 the organism have, without distinction, like nuclei con- 

 stituted by the same idioplasm. Oscar Hertwig indeed 

 ventures the assertion that each somatic cell if it were 



"Weismann: Das Keimplasma, eine Theorie der Vererbung. 

 Jena, Fischer, 1892. P. 43 and 268. 



