154 MENDELISM chap. 



two deeper shades of red or purple. But it may be hetero- 

 zygous for the purpling factor when it will throw the dilute 

 red (tinged white), or it may be heterozygous for either or 

 both of the two colour factors (cf. p. 44), in which case it 

 wiU throw whites. Of the picotees which come in such 

 a family, therefore, some will give picotees, tinged whites, 

 and whites, others will give picotees and tinged whites 

 only, others will give picotees and whites only, while 

 others, again, and these the least numerous, will give 

 nothing but picotees. The new variety is already fixed 

 in a certain definite proportion of the plants; in this 

 particular instance in i out of every 27. All that re- 

 mains to be done is to pick out these plants. Since all 

 the picotees look alike, whatever their breeding capacity, 

 the only wa^ to do this is to save the seed from a number 

 of such plants individually, and to raise a further genera- 

 tion. Some of them will be found to breed true. The 

 variety is then established, and may at once be put on 

 the market with full confidence that it will hereafter 

 throw none of the other forms. The all-important thing 

 is to save and sow the seed of separate individuals sepa- 

 rately. However alike they look, the seed from differ- 

 ent individuals must on no account be mixed. Provided 

 that due care is taken in this respect no long and tedious 

 process of selection is required for the fixation of any 

 given variety. Every possible variety arising from a 

 cross appears in the F2 generation if only a sufiicient num- 



