12 An Examination of Weismannism. 



favourable, and pass them on to the next generation 

 by heredity. That sexual propagation is well calcu- 

 lated to furnish congenital variations may easily be 

 rendered apparent. We have only to remember that 

 at each union there is a mixture of two sets of 

 germinal elements ; that each of these w r as in turn 

 the product of two other sets in the preceding 

 generation, and so backwards ad infinitum in an 

 ever doubling ratio. Remembering this, it follows 

 that the germinal elements of no one member of 

 a species can ever be the same as those of any other 

 member born of different parents ; on the contrary, 

 while both are enormously complex products, each 

 has had a different ancestral history, such that 

 while one presents the congenital admixtures of 

 thousands of individuals in one line of descent, the 

 other presents similar admixtures of thousands of 

 other individuals in a different line of descent. Con- 

 sequently, when in any sexual union two of these 

 enormously complex germinal elements fuse together, 

 and constitute a new individual out of their joint 

 endowments, it is perfectly certain that that individual 

 cannot be exactly like any other individual of the 

 same species which has been born of different parents. 

 The chances must be infinity to one against any single 

 mass of germ-plasm being exactly like any other mass 

 of germ-plasm ; while any amount of latitude as to 

 difference is allowed, up to the point at which the 

 difference becomes too pronounced to satisfy the 

 conditions of fertilization — in which case, of course, 

 no new individual is born. Hence, theoretically, we 

 have here a sufficient cause for all individual variations 

 of a congenital kind that can possibly occur within 



