Weismannism tip to date (189"). 133 



be mainly given in the phytogeny of any group of 

 multicellular organisms, while the latter supposes it to 

 be given mainly in each ontogeny. Galton's theory is, 

 that in each ontogeny only a small part of the stirp 

 derived from parents is consumed in making the 

 new organism — the larger part being handed over in 

 trust for passing on to the next generation, in the 

 same way as Weismann supposes to be the case with 

 germ-plasm. Darwin's theory, on the other hand, 

 does not entertain any such notion of " continuity " 

 in the substance of heredity from germ-cell to germ- 

 cell of parent and offspring ; it supposes that in 

 each successive generation the germ-cells are wholly 

 supplied with their germinal material from somatic- 

 cells of each individual organism. Or, adopting our 

 previous terminology, the three theories may be 

 ranked thus. 



The particulate elements of heredity all proceed 

 centripetally from somatic-cells to germ-cells (gem- 

 mules) : the inheritance of acquired characters is 

 therefore habitual. 



These particulate elements proceed for the most 

 part, though not exclusively, from germ-cells to 

 somatic-cells (stirp) : the inheritance of acquired 

 characters is therefore but occasional. 



The elements in question proceed exclusively in 

 the centrifugal direction last mentioned (germ-plasm) : 

 the inheritance of acquired characters is therefore 

 impossible K 



1 Professor Weismann still maintains that there is a further important 

 distinction between the theories of pangenesis and germ-plasm, in that 

 the one is pre-formative while the other is epigenetic. But I am still 

 unable to perceive that such is the case. He argues, indeed, that his 

 new doctrine of determinants emphasizes this distinction : the argument, 



