114 Theory of the Germ-Plasm 



far the most, of the cells of the plant-body have been 

 equally endowed in regard to latent characters. Turpin 

 and Schwann, later Miiller and Hanstein, but in recent 

 years, especially Vochting, have taken up the pen in the 

 support and development of this view. 



This prevailing and so well substantiated doctrine was 

 opposed by Weismann in the year 1885. He advanced his 

 well known theory of the continuity of the germ-plasm, 

 and thus sought to create a basis for a theory of heredity. 

 The material bearer of the hereditary characters in 

 their totality, and including therefore the latent ones, 

 Weismann calls germ-plasm ; the bearers of the active 

 qualities in any given cell, somatic plasm. The somatic 

 plasm is, therefore, lacking in no cell, because they are all 

 active to a certain degree, even if only to the extent of 

 being capable of further division. The germ-plasm, how- 

 ever, is, according to him, restricted to those cells which 

 are charged with the transmission of the hereditary char- 

 acters to the following generations. In the true somatic 

 cells this power is said to be lacking. 



Intimately connected with this conception, according 

 to Weismann, is the law that the character of every cell 

 is determined by its nucleus.^* The specific nature of a cell, 

 according to him, is dependent on the molecular structure 

 of its nucleus; every histologically differentiated kind of 

 cell possesses therefore its specific nucleo-plasm.^^ Identi- 

 cal nucleo-plasm, ceteris paribus, means also identical cell- 

 body ; in every somatarchic cell-division, as well as in most 

 of the somatic divisions, the nucleo-plasm must therefore 

 split into two unequal parts, only that part of the hered- 

 itary characters being given to each daughter-cell, which 



-*E. g. Die Kontinuit'dt des Keimplasmas. p. 30. 

 25L(7C. cit. p. 70. 



