194 DARWINISM TO-DAY. 



why exactly those variations needed for the development of 

 a certain adaptation appear at the right time ; third, how 

 correlation of adaptation comes to exist ; and fourth, how 

 variations are able to develop orthogenetically along a defi- 

 nite line, without depending on the necessity of a personal 

 selection raising them step by step." Weismann himself 

 refers to the theory as "a spring of definitively determined 

 variation." In 1902, Weismann further applied the theory 

 to the explanation of monsters, and other cases of terato- 

 genesis, of "sports" (sudden or large discontinuous varia- 

 tions), of suddenly appearing sex-characters, of specific 

 talents, and still other heretofore unsatisfactorily explained 

 phenomena. 



In defining the theory of germinal selection we come at 

 the very start to a difficulty based on the fact that little or 

 no reference has heretofore been made in this 

 and chemical* book to certain various theories or speculations 

 structure of as to the ultimate structure of protoplasm, espe- 

 cially the protoplasm of the germ-cells. In 

 recognising protoplasm as the "physical basis of life" (Hux- 

 ley's phrase), biologists have naturally tried to find in 

 its actual physical make-up some clue to its marvellous 

 capacities. The highest powers of our best microscopes, 

 however, reveal little more of this intimate physical struc- 

 ture than does our unaided eye. Probably the colloidal char- 

 acter of protoplasm, that is, its amorphous, non-crystalline, 

 viscous condition, is the most important physical fact about 

 it revealed by our closest examination. But this apparent 

 simplicity of physical structure is very unsatisfying to most 

 biologists, and they demand the assumption of an extremely 

 complex structure ; a subdivision of germinal protoplasm 

 into structural units and groups of units, just as the chemist 

 assumes, in his atomic theory, a subdivision of substances 

 into molecules and atoms. These protoplasmic units are, 

 of course, invisible ; like the atoms, they are beyond the see- 



