NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 105 



must depend upon internal properties of their hereditary quali- 

 ties. 1 ) 



I will now give briefly the necessary details concerning the 

 crosses mentioned in tables IX and X. As already mentioned, 

 all these crosses were made in 1913 with plants of the same origin. 

 For every cross a single specimen was chosen and some flowers on 

 the lower part of its main spike were castrated. The seeds were 

 sown in February 1914, the seedlings transplanted into boxes, and 

 from these, as a rule, about 25 specimens of each culture were 

 placed in a bed in April and May, giving them a good soil and 

 light exposure and plenty of space to insure a vigorous develop- 

 ment until the time of flowering and of fruiting. 



0. cana x 0. biennis Chicago. — A group of 71 specimens, all 

 of which produced high stems and 25 of which have flowered. 

 One was a mutant, combining the gray narrow leaves of 0. cana 

 with the marks of the stature, foliage and flowers of 0. lata. The 

 plants of the type of 0. cana were exactly like pure 0. cana at the 

 beginning of the flowering period, in July, when they had reached 

 a height of 70 cm. The remaining plants were like (0. Lamarcki- 

 ana x 0. biennis Chicago) laeta and velutina. The reciprocal cross 

 yielded 59 specimens, of which 5 remained in the condition of 

 rosettes. Of the remaining 54, about one-half or 25 have flowered, 

 the others reaching this stage approximately at the time when 

 they were pulled up and counted. One plant was a mutant, being 

 a metaclinous velutina, just as described in my book on pp. 308-31 1. 

 The others were densa and laxa, as should be expected, and agreeing 

 with these types throughout their whole life. 



0. cana x 0. Cockerelli.—A culture of 63 specimens, embracing 

 4 cana, 5 laeta and 15 velutina, which have flowered, and a large 

 number of rosettes of radical leaves. Two plants were mutants 

 of the type of 0. lata and one of them has flowered. Neither in 

 the rosette stage nor at the time of flowering have the plants of 

 the cana type showed any difference from ordinary 0. cana, the 

 characters of the father, also of its twin hybrid type, being invisible 

 in them. Such was the case in almost all the beds containing the 

 hybrids whose mother was cana, and this made the distinguishing 

 and counting of this type quite easy and sharply defined, and 

 therefore fully reliable. Short narrow leaves of a gray color, a 

 slender spike with long, thin flower buds with nodding tips were 



i) On these questions see Gruppenweise Artbildung, pp. 268 — 295, 1913. 



