0\ SOME HYBRIDISATION EXPERIMENTS 185 



green, that of the lilac-flowered red. Three crosses were made, and 

 all the Fi-plants were lilac-flowered with red stems. In F.. a segrega- 

 tion on the theoretical ratio 9 lilacs : 7 whites occurred. Some of the 

 white-flowered plants had their stems slightly tinged with red, the 

 others had green stems. Thus the segregation as to stem colour fol- 

 lowed the theoretical ratio 9 red : 3 slightly tinged with red : 4 green. 

 Two genes are supposed. A, which alone produces white flowers and 

 red tinged stem, and B, which alone produces white flowers and green 

 stem. When both A and B are present the flowers are lilac and the 

 stems red. aabb gives white flow;ers and green stems. In two crosses 

 out of five between a white-flowered F^-plant with red-tinged stem 

 and a white-flowered Fs-plant with green stem lilac-flowered plants 

 were produced as could be expected. 



2. A variegated plant of C. tinctoria was crossed with a self green. 

 The Fi-plants were green. In F.. segregation occurred on the theore- 

 tical ratio 3 green : 1 variegated. Thus only one gene for self colour 

 was involved. All the variegated plants were probably not of the 

 same genotypie constitution as a fourth of them were nearly yellow and 

 non-viable. In F^ from two variegated Fo-plants all the plants were 

 variegated but also here almost quite yellow, non-viable plants occur- 

 red. Therefore a gene, /, is supposed which increases the amount of 

 green in variegated plants, n'-plants then would be nVarly yellow, 

 non-viable. 



3. A plant of C. tinctoria with spots on the leaves of the upper 

 lip was crossed with a plant without such spots. Fi had spots. In 

 Fo segregation occurred on the theoretical ratio 3 spotted : 1 not 

 spotted. 



LITERATURE CITED. 



1. Baur, E. Untersuchungen über die Vererbung von Chromatophorenmerkmalen 



bei Melandrium, Antirrhinum und Aquilegia. Zeitschr. f. ind. Abst. u. Vererb. 

 IV, 1910. 



2. CoRRENs, C. Vererbungsversuche mit blass (gelb) -grünen und buntblättrigen 



Sippen bei Mirabilis Jalapa, Urtica piluJifera und Lunarin annua. Zeitschr. 

 f. ind. Abst. u. Vererb. I. 1909. 



3. Ikeno, C. Variegation in Plantago. Genetics II, 1917. 



4. Miles. F. C. A genetic and cytological study of certain types of albinism in 



maize. Journ. of Genetics IV, 1915. 



