GENETIC STUDIES IN POLEMONIUM COERLLEUM 21 



however, somewhat variable; in some i)lants they are completely 

 hidden behind the sepals. Both hermaphroditic plants — in which 

 consequently the stamens are much protruding (Fig. 3 a) — and 

 female plants show this micropetaly (Figs. 3 b and c). 



The hermaphrodite i)lants have long lilaments and the orange- 

 red anthers are big and tilled with pollen grains (Fig. 2 a), but 

 from this type a .series of steps lead over to a female type in which 

 the stamens are quite rudimentary and very small and short (Fig. 



2 c). In the »intermediate» types one or several of the stamens 

 are more or less developed (Fig. 2 b), but usually they do not 

 contain fertile pollen. Female and »intermediate» flowers sometimes 

 occur in the same inflorescence, and it seems as if outer conditions 

 have some influence upon the stage of development. 



In the micropetalous form I have not found female flowers 

 with rudimentary stamens, but only hermaphrodite flowers (Fig. 



3 a) and purely female flowers (Figs. 3 b and c) in which the 

 pistil is more or less abnormally developed, very often with several 

 styles of irregular shape (Fig. 3 c). These plants do not set fruit, 

 and artificial fertilization has been without result. 



SOME GENETIC EXPERIMENTS. 



In all my experiments the plants were protected against insect 

 visits by bags of muslin. Artifical cross-fertilization was produced 

 in the way that ripe anthers were taken off from a flower and rubbed 

 on the stigma of the castrated flower to be fertilized. By self-ferti- 

 lizing anthers from one flower were rubbed on another flower of the 

 same inflorescence; here the flowers were not castrated. 



The seeds were sown in the following spring in ordinary garden 

 soil in pots and the young plants later planted out in lots; next year 

 they flowered in June. Thus each generation takes two years for full 

 development. 

 1. The bipinimte form (P. coenileiim, v<ir. sihiricum). 



a. By self-fertilization of a blue hermaphrodite in 1917 I got (in 

 1919) 11 blue hermaphrodites and 1 blue hermaphrodite with 

 bipinnate leaves. The later (No. 500 b) was self -fertilized and 

 gave (in 1921) 32 bipinnate plants {F.), one of which (No. 575) 

 was again self-fertilized, and gave 18 bipinnate rosettes in 

 1922 (F3). 



b. One of the normal blue hermaphrodites of 1919 (No. 500 a) 



