170 Genetic Behaviour of the Hybrid Primula Kewensis 



The intermediate forms (M") are always heterozygous as far as our 

 experience goes, and throw all forms. 



Owing to the difficulty of classifying the plants, we know nothing 

 of the number of factors involved. 71/' is evidently recessive to all the 

 other forms. 



Colunr. In 1914 a new flower colour appeared in one of our 

 Kewensis families, very much paler than any we had seen before. It 

 apparently breeds true. We know nothing concerning the origin of 

 the parent of the plant which had the new colour. But in 1915 the 

 same colour appeared in the offspring of a cross between Kewensis and 

 a plant with a complicated ancestry, no. J-|. The results obtained fi-om 

 this plant are peculiar, and will be the subject of a separate account. 



Doubling. In Messrs Veitch's nursery a double variety has been 

 obtained. The account of its origin is of some interest. A plant 

 (PI. XXVI, fig. 5) with single and double flowers appeared, the double- 

 ness varying in degree. The double flowers were sterile, and the plant 

 was propagated by division. By repeating the process of division, 

 plants bearing only double flowers were obtained. 



Origin and genetic behaviuur of a new diploid form 

 exhibiting normal segregation. 



We now come to the most interesting case of segregation in 

 Keivensis. In 1911 we received from Me-ssrs Veitch two families of 

 Kewensis. 



A. Kewensis x fluribunda. Fy Five plants Kewensis. 



Four of these plants were selfed ; the seed of only one germinated, 

 giving two plants, one of which died before being described. The 

 other plant, no. |5, diffei'ed from other Kewensis in having a less robust 

 habit and long narrow ovate leaves. 



B. Kcivensis X flnribundavAr.isabellind. F^. Nine plants /'TeweHSj's. 

 Seed from eight of these plants was sown ; five gave no germination, 



one gave a large number of plants all Kewensis, and two gave a single 

 plant each. One of these was ordinary Keiueusis ; the other, numbered 

 f|, was ordinary Kewensis in appearance, but behaved very differently 

 genetically. Unfortunately the chromosomes of these plants were not 

 counted. Their genetic behaviour will be described on p. 177. 



