Improvement of a Hemi-Syncotyloiis Race. 4/7 



adapted to such an experiment in isolation. Our expe- 

 rience with the tricotylous races teaches us what to ex- 

 pect; for, obviously, either a half race or an intermediate 

 race must arise, if hemi-syncotyly is at all capable of 

 separate existence. 



But if such an isolation cannot be effected, i. e., if the 

 hemi-syncotyls are only minus variants of the syncotylous 

 intermediate race, the selection of hemi-syncotyls will 

 obviously do no more than maintain this latter race, and 

 only modify it slightly in the niuins direction. We should 

 then expect to obtain a strain which should not differ 

 essentially from a true syncotylous intermediate race, 

 except by a slight shifting of its mean value. In this 

 case the number of the hemi-syncotyls will be somewhat 

 increased by selection, but not, however, to the exclusion 

 of the syncotyls. 



From tliis discussion it is clear that we can furnish 

 the experimental proof that the hemi-syncotyls are minus 

 variants of the syncotyls by an appropriate experiment 

 in selection. For this purpose I started in 1890 with a 

 lateral branch of the pedigree on page 470, by selecting 

 every year only hemi-syncotylous plants as seed-parents. 

 I have continued this experiment in the same way for 

 seven generations, and the result was, as we shall see, 

 a confirmation of the above conclusion. 



This experiment was conducted in another garden 

 from that in which I cultivated the syncotylous race, but 

 otherwise carried out in exactly the same wav. In the 

 crops the hemi-syncotyls and the true syncotyls were 

 always recorded separately, so that for each seed-parent 

 two values were obtained. The individuals to be planted 

 out were at first chosen from two parents, but later only 

 from one ; the selection being made according to the pro- 



