486 



Mr. R. P. Gregory. 



course of breeding in the direct line from these plants the recessive types 

 have from time to time appeared. The course which this process of throw- 

 ing; recessives has taken is shown in the following; table : — 



Dominant character of parent. 



Recessive character. 



Generation in which the 

 recessive first appeared. 



Petals cut at the edges 

 (sinensis type) 



Dominant white 



Green stigma 



Magenta 



Palmate leaves 



Dominant white 



Magenta 



Thrum-eyed (short-styled) .. 

 Red stems 



GX Race. 



Petals heart-shaped with sim- 

 ple median notch (stellata 

 variety) 



Magenta flowers 



Red stigma 



Red 



Fern leaves 



GT Race. 



Magenta 



Red 



Pin-eyed (long-styled) 



Green stems 



F 5 

 F fi 



F 4 

 F„ 



In the character of the petals and in " dominant white " the dominance 

 of the positive factor is not quite complete and the heterozygous plant 

 can be distinguished from the pure dominant by inspection. In each of 

 these cases, the appearance of the pure recessive is given in the table 

 above, and in each case the heterozygote was recognised iu the preceding 

 generation. 



In the GT race one expected recessive type, the double flower, has not yet 

 appeared. But in F 3 two plants with semi-double flowers were obtained, 

 both of which would no doubt have produced doubles among their offspring, 

 had they not unfortunately succumbed to the attacks of fungus before they 

 ripened seed. 



It is obvious that some of the foregoing recessive characters have made 

 only a belated appearance in the progeny of the original heterozygous 

 plants. Both races of the tetraploid giants, however, produce a relatively 

 very small quantity of seed in self-fertilisation, so that the families raised in 

 each generation have nearly always been small. Consequently, in the 

 present state of our knowledge of the processes of segregation in tetraploid 

 plants, one cannot regard the sporadic appearances of the recessive types as 

 providing a clear indication that processes other than the normal ones are 

 involved. 



Besides the recessive types, both races of giants have thrown some 

 peculiar intermediate forms, which are distinct from any intermediate or 

 other forms known to me in the non-giant- diploid races. The characters, in 



