42 BIOLOGICAL SOCIETY OF WASHINGTON. 



transmitted the Lamarckian theory completely collapses, and 

 we must entirely abandon the principle on which alone Lamarck 

 sought to explain the transformation of species, — a principle 

 of which the application has been greatly restricted by Darwin 

 in the discovery of natural selection, but which was still to a 

 large extent retained by him. Even the apparently powerful 

 factors in transformation — the use and disuse of organs, the re- 

 sults of practice or neglect — cannot now be regarded as pos- 

 sessing any direct transforming influence upon a species, and 

 the same is true of all the other direct influences, such as nutri- 

 tion, light, moisture, and that combination of different influences 

 which we call climate. All these, with use and disuse, may 

 perhaps produce great effects upon the body (soma) of the in- 

 dividual, but cannot produce any effect in the transformation 

 of the species, simply because they can never reach the germ- 

 cells from which the succeeding generation arises" (pp. 387- 

 388). And much more in the same strain. 



Weismann fully admits the influence of the environment 

 upon the individual in producing marked changes. He also 

 fully admits the facts of adaptation to environment and the 

 transformation of species and development of organic beings. 

 But he insists that natural selection is competent to explain all 

 this, that it takes place through the selection of such accidental 

 variations in the germ as prove advantageous, or, as he puts it, 

 the selection from among an infinite number of ancestral germ- 

 plasms in the fertilized ovum of such as will produce an indi- 

 vidual most in harmony with its environment, leaving all others 

 in the latent state. This, as we have seen, is pure Galtonism. 



But this incapacity for the inheritance of acquired characters 

 is confined to metazoans or multicellular organisms — organisms 

 whose reproductive and somatic cells are differentiated. It 

 does not apply to protozoans or unicellular organisms. These 



