External Conditions and Hereditary Values. 485 
with 65 to 75% syncotylons offspring, and coulcl there- 
fore be brought back in one or two generations to the 
highest point attained by the original race. It is there- 
fore far removed even from the slightest semblance of 
a half race. 
How far, in the case before us, selection could lead 
in the course of years can, of course, only be surmised. 
But the sunflower is not a suitable species for the con- 
tinuation of these experiments, on account of the risk 
of occasional pollen grains of the ordinary sort being 
brought by insects from distant gardens ; for under these 
conditions selection would promptly extract a half race 
which would be the result of hybridization and not of 
selection, and artificial fertilization in the sunflower is 
beset with very great difficulties. 
13. THE INFLUENCE OF EXTERNAL CONDITIONS ON 
HEREDITARY VALUES. 
In these cultures my practice has been, first to record 
the seedlings in the pans and then to plant them out into 
pots with well manured soil, from which they were trans- 
planted to the beds in June. Here the plants stood at 
distances of over half a meter apart. As soon as axillary 
buds became visible they were removed, and only the 
terminal head was allowed to flower. Fertilization was 
left to insects, for my sunflowers do not set seed without 
crossing. As soon as the seed is ripe, I cut off the whole 
head in order to collect and clean the seed. 
The question presents itself, does this method of cul- 
ture exert any considerable influence on the proportions 
of syncotyls? In order to provide an answer I have in- 
stituted a number of subsidiary cultures in different vears, 
mr * 
