Varietäten, etc. — Physiologie. 243 



light yellow to daris yellow. The classes formed are: dark yellow, 

 yellow, light yellow, dark green, green, light green and yellowish 

 green; an exposition follows of the relation of environment to coty- 

 ledon colour and a study of the genetics of cotyledon color in Pisum 

 (historical, new data and theoretical Interpretation). The conclusions 

 and summary as given by the writer, run as follows: 



Variation in cotyledon color in Pisimi belongs to all three of 

 the categories of Variation mentioned in the forepart of the paper, 

 although there are no definite data as regards the origin of the 

 green cotyledon and the „recessive" yellow cotyledon varieties. 



1. Variations in cotyledon color due to environment are: 



a. Yellow cotyledon varieties producing seeds with green coty- 

 ledons, because of immaturity, absence of sufficient sunlight, excess 

 moisture at the period of ripening of the seed, etc. 



h. Green cotyledon varieties, especially those with wrinkled 

 seeds, producing seeds which fade or bleach to yellow or yellowish 

 green owing to excess of moisture and sunlight after the seed has 

 matured. 



2. Variations due to innate or hereditary differences probably 

 arising as mutations are: 



a. Different degrees or intensities of yellow and green coloring 

 in the different varieties of Pisum. These different intensities are 

 characteristic of particular varieties when all varieties under con- 

 sideration are grown under approximately the same environment. 



3. Hereditary distinctions as regards cotyledon color in Pisum may 

 be represented by the presence and absence of two factors, a factor 

 (I) causing green pigment to fade when the variety matures itsseed, 

 and a factor (G) causing the production of green pigment. All va- 

 rieties of Pisum so far experimented with , have yellow pigment in 

 their cotyledons and the determiner or determiners responsible for 

 this pigment may be graphically represented b}'' (Y). As the pre- 

 sence of green pigment masks yellow pigment, green may be regar- 

 ded as epistatic to yellow. 



4. The majority of varieties with yellow cotyledons when cros- 

 sed with varieties having green cotyledons, have yellow cotyledon 

 Fj offspring, the Fg generation breaking up into yellow and green 

 cotyledon plants in the ränge 3 Y : 1 G. 



The yellow cotyledon variety „Goldkönig" when crossed with 

 green cotyledon varieties has green cotyledon F^ offspring, in Fg 

 giving a ratio of approximately 1Y:3G, just the reverse of the 

 ordinary result. 



„Goldkönig" crossed with other varieties having yellow cotyle- 

 dons has yellow cotyledon F^ offspring, in Fg giving a ratio of 

 approximately 13 yellow seeds : 3 green seeds. 



With these facts in view, „dominant yellows" maj?" be repre- 

 sented by the formula YYGGII, „recessive yellows" (Goldkönig) by 

 the formula YYggii, and green cotyledon forms by the formula 

 YYGGii. These formulae account for all the facts so far discovered 

 in experiments on the inheritance of cotyledon color in Pisum, 

 except some data on linkage or coupling. These results will be dis- 

 cussed when more data are available. M. J. Sirks (Bunnik). 



Bevensee, E., Ueber die Fehler der Keimprüfungen. (53 

 pp. 80. Kiel 1914.) 



Der erste Teil der Arbeit befasst sich mit der theoretischen. 



