388 EXPERIMENTAL STUDY OF INHERITANCE 



ready for union, they have undergone a process of maturation 

 which may definitely affect the burden of hereditary quahties of 

 which each germ-cell is the vehicle ; by the process of amphi- 

 mixis or fertilisation a new integrate or zygote is formed — 

 the fertilised egg-cell — and in this integration the inheritance 

 may be affected by permutations and combinations, mutual 

 adjustments and new states of equilibrium, victories and defeats 

 of particular items, of all which we have no actual knowledge. 

 In the process of development, if there are several different sets 

 of primary constituents representative of a future structure — an 

 hypothesis from which we can see no escape — then the result 

 may in part depend on the struggles and interactions of these 

 in the course of development ; for, as we have often said, it does 

 not follow that everything represented in the inheritance finds 

 expression in development. Finally, it must be remembered 

 that the process of development implies interaction between 

 the inheritance and an appropriate environment, and that since 

 this appropriate environment is variable (within limits of the 

 embryo's viability) the result may again be modified by minor 

 peculiarities of nurture. It is, therefore, plain that prediction 

 as to individual results of crossing is out of the question. 



The Mendelian theory has thrown light on the variability 

 which has often been remarked when crosses have been effected. 

 Cross-breds are produced and inbred, and new forms appear in 

 their progeny. The MendeUans contend, in Mr. Bateson's 

 words, that " in aU the cases which have been properly examined 

 these new forms are created by simple re-combination of 

 characters brought in by the original parents." 



Mr. Bateson gives the instance of crossing a red variety of 

 some plant, say a stock, with a cream-coloured variety. The 

 red variety is characterised by red sap with colourless corpuscles, 

 the cream variety by yellow corpuscles in colourless sap. The 

 red is dominant (F^). But in the next generation (F^), we have 

 9 red, 3 red with cream, 3 white, and one cream. What is the 



