MISCELLANEA 



205 



Dr. Keeble's hypothesis, that it is starvation which induces 

 tbe appearance of male flowers in double begonias of the postu- 

 lated type M M F F and M m F f, and by imphcation that 

 it is high feeding which produces the development of female 

 flowers, while not inconsistent with the cases he had in view, is 

 yet not consistent with the fact that another variety of the same 

 plant, Begonia Gloire de Lorainc, so much cultivated as a stove 

 plant, forced under heat and richly fed, which produces only 

 male flowers until the end of the flowering season, when one or 

 sometimes two female flowers appear. The cultivation of the 

 melon furnishes another example of the appearance of abundant 

 male flowers in spite of rich feeding, the female flower being much 

 rarer and appearing later. 



The following is Mr. Keeble's scheme, showing the distri- 

 bution of the nine different types of zygotes among every 16 

 individuals, which accompanies his' paper in " Nature," Vol. 82, 

 No. 2104, February, 1910 :— 



MM 

 MM 



Mm 

 Mm 

 MM 

 M m 



Dihybrid 

 Scheme. 



< 



2. 



2. 

 4. 

 1. 

 2. 

 1. 

 2. 



m m 

 ni m 

 m m 



A Note on Mrs. R. Haig Thomas's Article 

 on Parthenogenesis. 



In her interesting paper on " Parthenogenesis in Nicotiana "' 

 in the Mendel Journal for October, 1909, Mrs. R. Haig Thomas 

 suggests that Nicotiana Sanderae may be simply the result of 

 parthenogenetically produced seed of N. Forgetiana, not the 

 result of crossing that plant with i\^. affini?, as has been alleged. 



The chief ground for her belief that N. Sandera? is not a hybrid 

 appears to lie in the fact that it breeds true from seed, a 

 " phenomenon which is not expected to occur, on Mendelian 

 principles of gametic purity and segregation." 



Now the authoress shows that N. Sanderat is capable of 

 forming seed parthenogenetically, and suggests that it is for this 



