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 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 variet}^ 



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 vears. 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 



