F. Keeble 187 



4. The giant arose suddenly and breeds true. 



5. It is now moderately fertile with its own pollen but proves 

 absolutely sterile when crossed with all other varieties (including the 

 parent form) of P. sinensis. 



(). Gigantism in P. sinensis is due to three factors and the character 

 is dominant to normal-character. 



7. Owing to the number of factors involved in the production of 

 the character of gigantism numerous semi-giant races exist. These 

 races intergrade one with another and hence their existence is not 

 generally recognized. 



8. Giants which breed true may be produced by crossing non- 

 giant races of P. sinensis. 



9. Fluctuating variations may owe their origin to the heterozygous 

 state of one or more factors in a form from the genetic constitution of 

 which is lacking entirely one of the factors for the production of a 

 Mendelian character. 



In conclusion, the author has pleasure in expressing his thanks to 

 Miss C. Pellew for her assistance during the early part of the experiment, 

 and to Mr G. Coomhs both for his kindness in drawing the figures in 

 the text and for much other help. The author has also to add that a 

 portion of the expense incurred in the plant-breeding experiments has 

 been met by a grant from the Royal Society. 



REFERENCES TO LITERATURE. 



1901. De Vries, Hdgo. Die Mutationstheorie. Leipzig, Bd. i. 



1909 a. Bateson, W. MendeVs Principles of Heredity, p. 19. 1909. Cambridge 

 University Press. 



1909 b. Bateson, W. Op. cit. "Translation of experiments in Plant Hybridiza- 

 tion." By Gregor Mendel, p. 337. 1909. 



1909. Gates, R. R. "The Stature and Chromosomes of Oenothera gigas, de 

 Vries." Archiv filr Zellforschwig, Bd. in. Heft. 4. 



1909. Gregory, R. P. "Notes on the Histology of the Giant and Ordinary Form 

 of Primula sinensis." Proc. Camb. Phil. Soc. xv. Pt iii. 1909. 



1909. Nilsson-Ehle, H. Krev.zungsiintersuchungen an Hafer und Weizen. 

 Lund. 4. S. 122. 1909. 



1910. Keeble, F. and Pellew, C. "The Mode of Inheritance of Stature and 

 Time of Flowering in Peas {Pisum sativum)." Jmirn. of Genetics, i. 1910. 



