The Isolation of Tricotylous Intermediate Races. 443 
81 82 86 
. , . 72 74 76 78 
A. Tricotylous offspring 
bo b/ 
44 48 50 
34 35 36 40 
B. Dicotylous offspring 24 25 25 
18 20 
The group is therefore dimorphic, the intermediate 
race is not yet pure. I found the same conditions to 
obtain in other cases. 
In Clark ia pulcliella also, the atavists reverted when 
sown in 1897 alongside the tricotylous culture already 
mentioned and from seed of the same parent. This 
parent already had a hereditary value of 64 %, but was 
the first in this race with a high figure, and therefore 
still belonged to the transitional period. The values are 
arranged in groups of 5 to 15, 15 to 25 etc., and the 
number of individuals which fall into each group are 
given under the mean percentage number, i. e., 10, 20 etc. 
Proportion of tricotyls in percentage 10 20 30 40 50 60 70 80 
Number of tricotylous individuals 02588 12 31 
Number of atavistic individuals 4 13 911 2 
The mean for the tricotylous individuals is 49%, for 
the atavists 30%. 
The race once isolated, the atavists obviously still 
have smaller values than the tricotyls; but the difference 
is never more than a small one, and the curve for the 
two races together will have only one apex. In Oeuo- 
thcra hirtella I examined a series of values of the atavistic 
offspring as well as the tricotylous offspring of the same 
parent of 1896 which had a value of 56%. This parent 
had been self-fertilized, the visits of insects having been 
excluded ; and so were all its offspring. I shall group the 
values in the same wav as above. 
