ORIGIN OF SPECIES 103 



posing that the seeds have stored more food materials, or 

 less, than they would have stored in their original habitat), 

 the inheritance of acquired characters would be proved. 

 Unfortunately, if we give the plants a few generations in 

 which to render their new features pronounced, we give 

 time for "natural selection" to obscure the result. 



The alternative to the doctrine of the inheritance of 

 acquired characters is not an explanation but a statement, 

 although it may be qualified by various mediate theories of 

 "germ-plasm," "heredity," etc. It is pointed out, as a 

 matter of common observation, that when two "gametes" 

 have fused into a "zygote," this fertilized cell grows into 

 an individual which reproduces neither of its parents with 

 exactness, nor is it, so to speak, the mean of the two. 

 Variation is therefore a fact, whatever may be its cause, and 

 since but a small fraction of all the zygotes produced 

 develop into plants or animals capable of reproducing in 

 their turn, nature eliminates all but favourable variations. 

 Of the variability of the zygotes we know nothing. We only 

 know that the individuals into which- they develop vary. 

 We cannot say whether, if the conditions as to supply of 

 food and incidence of external forces were identical, the 

 individuals would be identical, because such absolute iden- 

 tity of conditions is unattainable. We only know that the 

 zygotes contain a potentiality of variability, which, after all, 

 comes to the same thing. 



The "New Darwinism" has given rise to an extensive 

 literature, and many proximate theories, or rather formu- 

 laries, have been enunciated, but the main problem is still un- 

 solved. The doctrine of Natural Selection declares that fa- 

 vourable variations are perpetuated. The explanation which 

 is usually styled "Lamarckian" gives as the cause of vari- 

 ation the tendency of the offspring to inherit, in a more or 

 less pronounced degree, the characters acquired by its par- 

 ents. Weissmannism makes a tendency to vary an essential 

 quality of germ-plasm, but gives no explanation of its cause. 



