268 THE JOURNAL OF BOTANY 



carpels of the rogue wallflower until Professor G. Henslow, in 

 1910 or 1911, pollinated flowers of a rogue which occurred in his 

 garden at Leamington. '■ Some of the flowers he pollinated from 

 a red, others from a yellow variety. Both central and supple- 

 mentary carpels set seed, the former much more than the latter. 

 This seed was sown at Wisley and grown on to flower, the plants 

 produced being all alike, except in colour, and all normal. None 

 showed variation in number or form of petals, stamens, or carpels, 

 but both red and yellow flowers were produced, some of the 

 former with streaks of yellow. The normal type was thus clearly 

 completely dominant to the rogue. We do not know to which 

 colour type the original rogue belonged. 



Seed was saved from these plants interpollinated and sown as 

 soon as ripe. Some of the resulting plants flowered in 1913 and 

 showed that the seed had given rise to two types, the normal and 

 the rogue, but as many had not arrived at flowering size they were 

 all grown on to flower in 1914. A few plants died from one cause 

 or another, but 143 flowered, and of these 101 were of the normal 

 type (both red and yellow) and 42 of the rogue type (both red and 

 yellow). On the assumption that we have to deal with a simple 

 3 to 1 Mendelian segregation, the expectation would be 107 

 normals and 36 rogues, and the numbers obtained are sufficiently 

 near to the expectation to suggest that simple segregation is 

 taking place. 



The case is a particularly interesting one, for the differences 

 between the two forms are marked and complex, and the fact that 

 the dominance is complete is in itself very interesting. As we 

 have said, the change from maleness to femaleness is a rare one, 

 but the results of the experiment seem to show that in CheirantMis 

 femaleness is recessive to maleness. 



The persistence of this rogue type in small numbers, even 

 though now great care be exercised in eliminating them from 

 plants growing for seed, may be readily understood, if we assume 

 the rogue on its first occurrence produced seed.f The seeds 

 produced by it must have been hybrids, since the rogue itself 

 produces no pollen, but they would doubtless have been sown 

 among others from perfectly normal plants, and the culture 

 would consist of many true normals, and a few hybrids, apparently 

 normal, and quite indistinguishable from the normals in structure. 

 The normals would far outnumber the hybrids, and the chances 

 of interpoUination among the latter would be correspondingly 

 small, with the result that, while hybrids would be produced with 

 each succeedmg generation, rogues — the pure recessives — would 

 rarely appear. 



We may show this graphically by the following diagrams, 

 where N stands for the dominant normal, r for the recessive rogue. 



Crossing the rogue with the normal (which can be done only 

 one way) we have : 



* Journal R.H.S. xxxviii. p. xxxix. (1912). 



t Roguea allowed to grow among plants produce a few seeds without 

 artificial pollination. 



