472 Syncotylons Races. 



used the plants with a mean value (say 50-55% ) for the 

 continuation of the culture. But then I would have ob- 

 tained a non-selected strain, and the figures for the first 

 two generations following on the original plant, clearly 

 indicate that this mean would have been about 50-55%, 

 which is also, as we know% the mean value for tricotylous 

 intermediate races. 



The figures given in the pedigree do not present a 

 complete picture of the whole improved race, for in each 

 year the hereditary value of the best offspring alone was 

 determined. Dicotylous seedhngs and those with a low 

 degree of fusion in the seed-leaves were excluded from 

 further cultivation, as were also weak plants. If I had 

 not applied this selection, the mean values would ob- 

 viously have turned out somewhat lower; but the differ- 

 ence would not have been a very considerable one, as the 

 next two sections will show. 



The chance of obtaining a pure syncotylous progeny, 

 i. e., a crop v/ithout dicotylous seedlings, may appear 

 to be very great in this experiment. In 13 individual 

 crops 96% and over was reached. But appearances 

 are deceptive. Only once did I have a perfectly pure 

 crop (100%) and that even at the outset of my experi- 

 ment, in 1890; but this plant had produced only 105 fer- 

 tile seeds ; and of course we must acknowledge the possi- 

 bility of some stray atavistic seedlings occurring amongst 

 them if the harvest had been larger. In other words, 

 selection leads the race as close as possible to the highest 

 degree of purity, without, however, enabling it to reach 

 it. Moreover, the table shows at a glance, that the pro- 

 geny of the plant with 100% would probably haAC fallen 

 back from this high value, in the case of many of its 

 offspring at any rate. 



