DOUBLE STOCKS. 



75 



more rapidly and vigorously than the singles, and that where the 

 period of development is sufficiently prolonged, selection based on 

 this difference can be used as a means of securing a higher proportion 

 of doubles in the beds than corresponds with the actual output from 

 the parent plants." 



Here it is to be observed the conscious selection of the more vigorous 

 seedlings is advocated as a means of securing an abnormally high per- 

 centage of doubles, and Miss Saunders suggests that similar selection 

 carried out unconsciously accounts for the high percentages of doubles 

 often claimed and doubtless obtained. 



An extensive trial of stocks at Wisley in 1916-17 gave us an 

 opportunity of testing upon a fairly large scale and with a great 

 diversity of stocks how far this selection of the most vigorous plants 

 carried out by workers without great experience in selecting stocks 

 for doubleness would result in obtaining abnormally high percentages 

 of doubles. As Miss Saunders has pointed out in her paper already 

 quoted, " the actual output of doubles among strains of Stocks now in 

 cultivation does not on the average exceed 56-57 per cent., and should 

 perhaps be put somewhat lower — possibly 53-54 per cent." 



The method adopted was as follows : The seed of each strain was 

 thinly sown in a pot of soil which had been very thoroughly mixed so 

 as to avoid as far as possible any inequalities. When the seedlings 

 of each strain were large enough they were pricked out into a box in 

 order of vigour and grouped in three categories — vigorous, medium, 

 and weak. The number of plants in each of the three categories 

 varied greatly with the different strains, but the grouping was done 

 by one of us in every case, so that the same standard was kept up all 

 through. When large enough some of the plants were removed from 

 the boxes into pots, and again potted later into their flowering pots. 



It soon became evident that after pricking out into boxes the 

 vigorous plants did not in every case maintain their lead. At potting 

 time indeed it not infrequently happened that several of those which 

 at pricking-out time were placed in the weak group were more vigorous 

 than the primarily vigorous ones. In all cases the most vigorous 

 plants were chosen from the boxes for potting on, irrespective of their 

 original classification, but note was kept of the place originally occupied 

 by every plant in the original classification, so that the character not 

 only of the plants most vigorous at the potting-on time could be 

 determined as far as doubleness went, but track could also be kept 

 of the fate of those in the different groups at pricking-out time. The 

 plants left in the boxes were kept to flower in them so far as they would- 

 Plans were made of every box (fig. 22), and the character of each 

 plant noted as it came into flower, whether in a pot or in a box, and 

 in this way the ultimate fate of each group was ascertained. 



Of the plants pricked out into boxes a few died either in the boxes 

 or after being potted up ■ and unfortunately a large proportion of 

 those left behind in the boxes at flowering time failed to flower. 



The following Table shows the numbers at pricking-out time of 



