22S 



Gates. 



mutant; and since Lamarckiana is generally admitted to be speci- 

 fically distinct from grandi flora as regards its characters; and since, 

 further, the two forms are unlike each other in every stage of ontogeny; 

 we may justly regard this as an interspecific cross. The great number 

 of character-differences involved is made obvious in the Fg hybrid 

 offspring. It should further be noted that a typical dominant unit- 

 character, namely, the red pigmentation, and a typical recessive unit- 

 character, namely, dwarfing, are present in one of the parents of each 

 cross, the dwarf character being in a recessive or latent condition. 



Fig. II. Fj rosette, gr audi flora X riibiicalyx. 



The differences in fohage, habit and physiological develepment are, 

 on the other hand, in no sense unit-characters, but very complex 

 differences such as distinguish well-marked or aggregate species. The 

 contrast between these two types of characters in the Fi and Fg 

 hybrids is very striking. 



D. 0. grandiflora x 0. mut. rubricalyx and its reciprocal. Fi 



These forms are quite fertile with each other, as are also the Fi 

 and Fo hybrids. Seeds appear to be produced by these hybrids quite 

 as plentifully as from the parent races. The Fi plants were all grown 

 at St. Louis in 1911, and the F, all in the English climate last year. 



