6o MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 



De Vries (1900, p. 86) described a case of vegetative mutation in a hybrid 

 between Veronica lonqifolia, which has a blue flower, and V. alba with a 

 white flower. The hybrid has a blue flower, but several cases w^ere noted in 

 which the entire buds or portions of inflorescences produced white flowers. 

 These w'hite sports, when self -fertilized, produced white flowers only, in the 

 preliminary tests cited. 



Similar vegetative splitting is known in Datura hybrids, being seen by 

 Naudin in 3 individuals only, while sports of this character of Brassica, Raph- 

 aniis, Abies, Anagallis, Helianthemiim, Zca, and Cytisus are well known. 

 Nearly all other sports of hybrids are clearly of an atavistic nature, being 

 more or less direct reversions, sometimes rehearsing the juvenile characters 

 of one of the parents of the hybrids. 



A second instance was offered by a form known as 0. ammophila. This 

 material was grown from seeds obtained from Professor W. O. Focke, which 

 had been collected on the coast near Bremen, Germany. 



A large number of seeds were sowm in sterilized soil in the propagating 

 house on February 10, 1905. A month later the seedlings obtained were 

 examined and a dozen representing the widest visible range of variation were 

 transferred to pots, while the remainder of the culture was discarded. With 

 successive repottings the number of individuals was reduced to 7, which were 

 transplanted to the experimental garden in the latter part of May, at which 

 time no differences of moment were noticed. During the summer 3 of the 

 specimens sent up shoots, while the other 4 formed dense rosettes with a few 

 short lateral branches. 



About the middle of August the more advanced individuals came into 

 bloom. Xo careful examination of them had been made up to this time, 

 but it was now seen that one of them had formed a lateral branch at the 

 base of the main stem, which, by the spread of its branches, the shape and 

 expansion of its leaves, and its general vigorous growth had become the larger 

 member of the shoot. This branch, in the form and behavior of all of its 

 organs, including flowers and fruits, was an exact reproduction of the O. 

 biennis which has formed the basis of cultures under that name in the New 

 York Botanical Garden. Branches of the sport and of typical biennis were 

 submitted to several botanists, with the result that they were found to be 

 indistinguishable by anatomical characters. 



The main stem, which had branched in the usual manner, had been crowded 

 from its natural upright position and had assumed a half-recumbent position, 

 having the appearance of a lateral branch. 



The suggestion hes near at hand, that 0. ammophila is a hybrid derivative 

 of 0. biennis, and that the vegetative mutation is simply one of reversion, after 

 the manner of examples cited above. No positive evidence upon the origin of 

 ammophila is at hand, however. 



