PLANT HYBRIDIZATION BEFORE MENDEL 



3^9 



"The pollen grains and egg cells of the monohybrids are not hybrids, 

 but belong purely to the one or the other of the two parental types. For 

 di-polyhybrids the same holds good, in relation to every character re- 

 garded by itself." {ib., p. 86.) 



De Vries then proceeds to the now well-known statement of 



the situation in a hybrid, as regards the pollen and egg cells, in 



the representation of the dominant and the recessive characters, 



which is substantially as previously stated by the author in the 



Comptes Rendus, except for the addition of the following general 



statement : 



"in the simplest case, the splitting manifestly occurs in equal halves, 

 and one gets : 



50% dom. + 50% rec. pollen grains, 

 50% dom. + 50% rec. egg cells." (p. 86.) 



For the existence of 75 per cent with the dominant and 25 per 

 cent with the recessive character among the progeny of a mono- 

 hybrid, De Vries adduces data from his own experiments with a 

 considerable number of species. He says : 



"This composition I found to be verified in very many experiments." 

 {ib., p. 87.) 



In addition to the crosses reported In the Comptes Rendus, De 

 Vries cites the following ratios, giving in each case the year of 

 the cross. Some of these were also given in the brief note in the 

 Comptes Rendus. 



1. A. BY ARTIFICIAL CROSSING 



