Eeactions and Products in Inteespecific Crosses 183 



I have given data iu the preceding pages to show that these species, of which I 

 have made use in my experiments, are in no respects special cases in any way, but 

 that in the principles of reaction in crossing they show the same phenomena that 

 De Vries so clearly puts into two categories, which without extensive testing 

 appear to justify this distinction ; but in the examples that I have had to test 

 there appears no true distinction. Breeding true is not a test, and instances that 

 have been classed as unisexual must, I think, be adequately tested before it be 

 admitted that they show a special type of reaction. Throughout, the crossing of 

 species is fully in accord with the principles of factorial composition and action, 

 and in this the Mendelian reaction appears most prominent as a method of 

 analysis. 



