Combination of Hereditary Characters 25 



and in any proportion. This is shown in variegated leaves 

 and striped flowers, where the result of this combination, 

 after corresponding splitting, is almost directly demon- 

 strated to us. Almost endless is the diversity of pattern 

 of variegated leaves, frequently on the same plant, or at 

 least on the different individuals of one and the same 

 crop. Striped flowers, according to Vilmorin, arise 

 through partial atavism from old white-flowering varie- 

 ties of red or blue species. 10 Young varieties usually re- 

 vert by leaps to the ancestral form, while the older ones 

 do so by steps, through the appearance of isolated stripes 

 of the original color on the white back-ground. It is as 

 if the color potentialities were already too much weakened 

 to tint the whole corolla in one effort. The descendents 

 of the first striped flowers, however, soon form broader 

 stripes, and finally return, after a few generations, [at 

 least in some specimens, 11 ] to the uniform color of the an- 

 cestral form. 



Extremely peculiar are those cases where hereditary 

 potentialities, which in the active state necessarily ex- 

 clude each other, occur together in a latent state. Instead 

 of giving a long enumeration of many cases, I prefer to 

 describe a well-known case of variability, and select for 

 the purpose the arrangement of leaves in whorls. 



Two-ranked whorls, the leaves of which stand cross- 

 wise over each other on the successive nodes, belong to 

 the best and most constant characteristics of entire nat- 

 ural families. Less frequent are the cases of three- and 

 more-ranked whorls. Quite frequently, however, one 



10 Vilmorin, L. Leveque de. Notices sur V ameliorations des 

 plantes par le semis, pp. 39-41. 1886. (According to modern views 

 the stripes are due to a separate character, de V. 1909.) 



"Matter in the body of the text in brackets has been introduced 

 anew into the translation by the author of the original. Tr. 



