314 Ever-sporting Varieties 



This may best be done by determining the de- 

 gree of inheritance for the various constituents 

 of the race during a series of years. It is only 

 necessary to apply the two precautions of ex- 

 cluding all cross-fertilization, and of gathering 

 the seeds of each individual separately. We do 

 not need to ascertain whether the variety as 

 such is permanent; this is already clear from 

 the simple fact of its antiquity in so many 

 cases. We wish to learn what part each in- 

 dividual, or of each group of individuals with 

 similar characters, play in the common line 

 of inheritance. In other words, we must 

 build up a genealogical tree, embracing several 

 generations and a complete set of the single 

 cases occurring within the variety, in order to 

 allow of its being considered as a, part of the 

 genealogy of the whole. It should convey to us 

 an idea of the hereditary relations during the 

 life-time of the variety. 



It is manifest that the construction of such 

 a genealogical tree requires a number of sepa- 

 rate experiments. These should be extended 

 over a series of years. Each should include a 

 number of individuals large enough to allow 

 the determination of the proportion of the dif- 

 ferent types among the offspring of a single 

 plant. A species which is easily fertilized by 

 its own pollen, and which bears capsules with 



