372 EXPERIMENTAL STUDY OF INHERITANCE 



tion, vol. ii. p. 394), in which one-half or one-quarter of the body 

 is like that of the male and the other half or three-quarters like 

 that of the female, may be due to an inadequate blending of the 

 male and female nuclei. "They may separate completely at 

 the first or at some subsequent division of the segmentation 

 nucleus, and thereafter each may control a certain fraction of 

 the developing organism, yielding a lop-sided result." 



4. The maternal and paternal contributions may remain 

 together in the development of the body, though one is dominant, 

 but they may be dissociated in the formation of the germ-cells, 

 so that two sets of germ-cells result (Mendelian inheritance). 



5. The maternal and paternal contributions may find equal 

 expression in development, and through them ancestral con- 

 tributions may also find realisation (Galtonian inheritance). 



There should not, of course, be any opposition between Men- 

 delian and Galtonian formulae, for that is a confusion of thought, 

 to obviate which we have sharply separated the statistical from 

 the experimental study of inheritance. They are correlated, 

 and ultimately they will be seen in complete harmony, as different 

 aspects of the same phenomena. But it is simply muddle-headed- 

 ness which can find any opposition between a statistical formula 

 applicable to averages of successive generations breeding freely, 

 and a physiological formula applicable to particular sets of 

 cases where parents with contrasted dominant and recessive 

 characters are crossed and their hybrid offspring are inbred. 

 We may refer to the admirable essay by Darbishire (1906). 



6. Practical Importance of Mendel's Discovery 



As Mendel's discovery is extended it is bound to have a great 

 influence on the breeding of animals and the cultivation of 

 plants. Wherever it is applicable it will afford a solid basis 

 for action, enabling the breeder to reach his desired result more 

 surely, more rapidly, and more economically. The case we have 



