232 Plant-Breeding 



very soon obliterated if the given progenitor is different 

 from the bulk of its ancestors." 



8. The crossing of plants should be looked upon as a 

 means or starting-point, not as an end. We cross two 

 flowers and sow the seeds. The resulting seedlings may 

 be unlike either parent (see Fig. 57) . Here, then, is varia- 

 tion. The operator should choose that plant which most 

 nearly satisfies his ideal, and then, by selection from its 

 progeny and the progeny of succeeding generations, gradu- 

 ally obtain the plant which he desires. It is only in plants 

 which are propagated by asexual parts as grafts, cut- 

 tings, layers, bulbs, and the like that hybrids or crosses 

 are commonly immediately valuable ; for in these plants 

 we really cut up and multiply the one individual plant 

 which pleases us in the first 1 batch of seedlings, rather than 

 to take the offspring or seedlings of it. Thus, if any par- 

 ticular plant in a lot of seedlings of crosses of cannas, or 

 plums, or hops, or strawberries, or potatoes, is valuable, 

 we multiply that one individual. There is no reason for 

 fixing the variety. But any satisfactory plant in a lot of 

 seedlings of crosses of pumpkins, or wheat, or beans, must 

 be made the parent of a new variety by sowing the seeds 

 of it and then by selecting for seed-parents, year by year, 

 those plants which are the best. "The unsettled forms 

 arising from crosses," Focke writes, "are the plastic 

 material out of which gardeners form their varieties." 



But even in the fruits, and other bud-propagated 

 plants, crossing may often be used to as good advantage 

 for the purpose of originating variation as it may in peas 

 or buckwheat. It only requires a longer time to fix and 

 select variations because the plants mature so slowly. 



