PLANT HYBRIDIZATION BEFORE MENDEL 217 



are "true species," and that the same is the case for some varieties 

 of peas, and that, in the case of Phaseolus multiflorus and several 

 so-called sub-species of P. vulgaris^ and in most of the white- 



Plate XXXVIII. Hermann Hoffmann. Professor of Botany at the University of Giessen 



(1855). 



flowered varieties of blue or red-flowered species, and in a variety 

 of Pisum sativum^ color is not fixable. 



Variation and the results of crossing are briefly discussed in the 

 case of 159 genera. Among these, under "Geum" (No. 71, 



