No. 597] 



EXPERIMENTS WITH PETUNIA 



tained as with the commercial material. F x was mixed, 

 the numbers recorded being 225 singles and 113 doubles. 



So far, then, the material employed has furnished no 

 exception to the statement that singles crossed with the 

 pollen of double x yield some doubles in b\ though breed- 

 ing true to singleness when self-fertilized or pollinated by 

 other singles. 



Unfortunately very little evidence is yet available as to 

 the results of using the double plant as the seed-parent. 

 Haagedoorn's plant was of an exceptional character and 

 the Ventura plants, though more typical, showed con- 

 siderable sterility. Only 5 plants were raised from the 

 seed sent by Mrs. Francis. These were all double. Only 

 one individual was obtained by self-fertilization of these 

 plants and this was also double. A cross with a single 

 (Countess of Ellesmere) produced only one offspring and 

 this plant was lost before flowering. It is however hoped 

 by a repetition of this mating to obtain an F, generation 

 which will throw further light on the relation of the 

 double to the single. 



The following information received from Professor 

 Bateson concerning a cross made at the John Innes 

 Horticultural Institution by E. J. Allard unfortunately 

 only came to hand after the above account had been for- 

 warded for publication. In the mating in question a 

 nyctaginiflora plant, one of a batch raised from a sample 

 of the same wild seed as that from which my own plants 

 were grown, was crossed with pollen from a pink-flowered 

 double, a florist's highly cultivated type of plant. More 

 than 20 plants were raised in F, and all were single. If 

 we consider this number large enough to be taken as con- 

 clusive we should have in this experiment an exception to 

 the results hitherto obtained and summed up in the gen- 

 eral statement formulated above. We must then suppose 

 that there exist in these Petunia forms certain single a ml 

 doubles the relation between which is such that .ImiMe- 

 ness completely disappears in the F x generation obtained 

 from a cross between them. 



