552 



THE PURE LINE HYPOTHESIS. 



In the accompanying table the famiHes are arrano-ed in the 

 order of increasing mean leaf-width. The total rang-e has now 

 considerably increased. In the parent hybrids the rang^e was 

 50-84 mm., while in the offspring it was 20-91 mm. An inspec- 

 tion of the distribution of the dift'erent families will show that 

 there is some sign of an imperfect segregation into plants with 

 small leaves and plants with large leaves ; the break in the series 

 tends to be in the neighbourhood of 40-55 mm. 



There is some correlation Ijetween habit, variegation and 

 leaf-size. In the table the numljer of symbols (°) above the 

 figure indicate the number of plants which were dwarf, the 

 remainder being straggling. The symbol (*) indicates a varie- 

 gated plant : when placed above ( ° ) it implies that the dwarf 

 plant was variegated. 



The dwarf plants of a family tended to have smaller leaves 

 than the straggling plants ; thus the mean leaf-width of the 33 

 dwarfs was 44 mm., and of the 1 1 1 stragglers, 65 mm. Also, 

 variegated plants tended to have smaller leaves than non- 

 variegated plants, whether they were dwarfs or stragglers, as is 

 seen in the accompanying table : 



19 Families, 14 1 Offspring. 



Variegated dwarf plants had a mean of 42 mm. against non- 

 variegated dwarfs, 48 mm. ; while variegated stragglers had a 

 mean of 57 mm. against non-variegated stragglers, 66 mm. 



We accordingly see that variegation in the offspring was not 

 necessarily confined to the dwarfs, although the variegated grand- 

 parent S was dwarf, and the non-variegated grandparent ? 

 was straggling. Nevertheless the relative number of variegated 

 plants was greater among the dwarfs than among the stragglers. 

 Thus there were 70 per cent, variegated offspring among the 

 dwarfs and only 15 per cent, among the stragglers. 



