GERMINAL SELECTION 159 



Weismann postulates a distinction between the 

 soma plasm, which dies with the organism, and the 

 germ plasm, which survives in the offspring and is 

 therefore continuous and immortal. Weismann con- 

 siders the latter as a special and independent sub- 

 stance and thus reaches the second part of his theory 

 which is, not only open to severe criticism, but could 

 lead, if it were strictly adhered to, to inadmissible 

 consequences. 



The fundamental postulate of the theory is that 

 the somatic elements of the organism can exert no ■ 

 influence upon the germinal elements, as the two kinds 

 are separated from the very first stage of ontogene- 

 sis. Consequently the germ plasm of the offspring 

 is made up solely of the parents' germ plasm, bar- 

 ring, of course, modifications brought about by the 

 liberation of polar particles and by fertilisation. 

 These modifications, however, result merely from a 

 reshaping of elements which existed previously in the 

 ancestors; they cannot, therefore, add any new ele- 

 ment to the make-up of the species. But whence 

 come the variations, however slight they may be, 

 which give rise to a new species? The evolution of 

 higher animals grows to be unaccountable, and ap- 

 pears, in fact, impossible; f orjthere is no reason why 

 our germ plasm should differ from the plasm of our 

 Protozoan ancestors. 



By admitting in his later writings the influence of 



