WEISM ANN'S THEORY OF THE GERMPLASM 97 



mann's doctrine of determinants fails when we 

 analyse the formation of the blastosphere, the 

 gastrula, and the germinal layers. 



The formation of the blastosphere seems to me 

 to be due to the co-operation of the following 

 processes : 



(1) In the division of the egg- cell cavities arise 

 between the four, eight, and sixteen pieces, and 

 thus the whole contents of the egg become arranged 

 more loosely. (2) The more the cells multiply by 

 division and become smaller in circumference, the 

 more closely they apply their lateral surfaces to 

 each other, especially at the outer surface of the 

 whole, so assuming the arrangement of cell-epithelia. 

 (3) By the secretion of iiuid, a constantly growing 

 central cavity is formed pari passu with the 

 approximation of the superlicial cells, and this 

 probably also brings with it an increase of the 

 internal pressure, and a wider curvature of the wall 

 of the sphere. 



Now, is there any part of these processes that has 

 to do with the breaking of the nuclear contents 

 into groups of determinants with different qualities ? 

 By no means. The egg divides into many pieces, 

 because such division is a general property of cells, 

 and it is not associated with separate, special 

 material bearers. The appearance of spaces between 

 the cells, resulting from division, is due to forces 

 some of which reside within the single cells, some 

 of which come from without. In especial, the 

 assumption of a spherical shape an assumption 

 occurring also to a greater or less degree when the 



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