336 ON ATAVISTIC VARIATION IN OENOTHERA CRUCIATA. 



cultivation, and of the hybrids, I hope to solve this in some years; 

 but as to the chances of getting exceptions, it is evident that these 

 are only small and that it would be preferable if the same experi- 

 ments were made by a number of investigators. 



The aim of such experiments would be to repeat artificially the 

 production of 0. cruciata varia and by this means to throw some 

 light on its origin in particular and on the origin of inconstant varie- 

 ties in general. With a view to the possible repetition of this cross 

 I will now give a description of the inheritance of the broad and 

 linear petals in this variety. In so doing I limit myself to the detailed 

 exposition of a single experiment carried on with the descendants of 

 one original specimen of my variety. 



In the year 1897 this plant was raised from seed obtained in the 

 usual way of exchange between botanical gardens. I obtained but 

 a single specimen, which bore all the characteristics of the typical 

 0. cruciata. The spike, before the opening of the flowers, was placed 

 in a bag of prepared parchment paper to prevent any visits from 

 bees. The anthers touch the stigmas when opening, and the flowers 

 fertilize themselves without any aid. In the same way I always 

 took care to collect each year purely pollinated seeds only. 



This original plant bore but a few seeds, from which during the 

 next year I obtained only sixteen flowering individuals. But this 

 number was sufficient to show the whole range of the variability of 

 the race. Nine plants bore typical cruciate flowers with linear 

 petals, two specimens had broad obcordate petals like those of 

 0. muricata, and the five remaining had an intermediate breadth, 

 varying in all degrees between these two extremes. Even on the 

 same spike the petals of the different flowers were in this regard 

 unlike each other, and sometimes of the four petals of one flower 

 some were narrow and others broad. I also found petals large on 

 one side of the median nerve and small on the other side. 



I obtained pure seed of some of the narrow-petalled ones and 

 of some of the intermediate specimens, separately for each plant, 

 and the next year (1899) had four groups flowering. Two of 

 them from two typically cruciate mothers repeated this type only, 

 each group in thirty plants. One group, also from a cruciate mother, 

 produced twenty-two typical and eight atavistic individuals, mea- 

 ning thereby those with broad obcordate petals. Intermediate 

 types were wanting. So it was with the fourth group, the children 

 of an intermediate mother, of which only four were purely cruciate, 

 the remaining fifty-eight being atavistic. 



