Tricotylous Races. 456 
outside. I collected the seeds and determined the values 
in the same way as usual, and obtained the figures which 
appear in the following summary : 
HEREDITARY VALUES IN ANTIRRHINUM MAJUS. 
Percentage values 1-4 10 20 30 40 Mean 
Dicotyls in the shade 4 2 2 2 20% 
Dicotyls in the sun 5 8 4 1 4 14% 
Tricotyls in the shade 3 2 3 4 35 % 
Tricotyls in the sun 1 14 9 14% 
Number of seed-parents 10, 21, 12 and 24. 
We see that in both cases the proportion of tricotyls 
was considerably increased by cultivation in the shade. 
The experiments which we have passed in review in 
this section prove that the proportion of tricotyls in the 
offspring may be considerably modified by external in- 
fluences, especially in eversporting varieties, but within 
certain limits. The differences are such as cannot be 
neglected in comparative experiments and cultures, and 
show the importance of carrying out the latter under as 
constant conditions as possible. In general it must be 
assumed that a treatment, favorable to the individual 
flowers and seeds, will increase the production of tri- 
cotylous seedlings, but the question as to the nature of 
this relation in the individual cases must, for the present, 
remain unanswered. 
