The Isolation of Tricotylous Intermediate f\accs. 439 
these plants 25 set seed, but the culture was unsuccess- 
ful in this year, owing to adverse circumstances, and 
only a few of the plants produced more than 200 fertile 
seeds. The values, therefore, were not very exact, but 
formed a close group ranging between 18 and 56%, 
with a mean of 32%. It will be seen that in spite of the 
selection a general retrogression had taken place. 
Sun unary. If we look at the results of the experi- 
ments which have been described, we are struck by the 
fact that a certain group of hereditary values appears 
much more commonly than others. These are the fig- 
ures ranging round 55%, and this value is usually 
reached at the conclusion of the second generation or, 
in less favorable experiments, at the conclusion of the 
third or fourth. AYith a view to emphasizing this fact 
I have grouped the whole series of experiments in such 
a way that the figures round 55% are brought together 
in one column : 
ISOLATION OF TRICOTYLOUS INTERMEDIATE RACES. 
HIGHEST HEREDITARY VALUES EXPRESSED IN PERCENTAGES FOR THE 
SUCCESSIVE GENERATIONS. 
FIRST GEN- 
ERATION 
1-50 c r 
ABOUT 
55% 
60-95 % 
Antirrhinum inajus . 
1892 
1 
8 
25 
41 
79 
79 

Mercurialis annua . 
1892 
I 

2 
55 
86 
92 
91 
Silcne inflata .... 
1892 
I 
3 
32 
55 
73 
56 

Cannabis sativa . 
1893 
I 
3 
15 
52-63 
80 
90 

Clarkia pulchella . 
1895 

I 
16 
64 
79 


Helich rysu in bracteatum 
1895 

I 
41 
51 
52 


Pa paver Rhoeas . 
1895 

I 20 
56 
75 


Phacelia tanacetifolia, . 
1895 

I 14 
58 
90 


Oenothera hi rt el la 
1895 

I 
8 
56 
89 


In this table the first column gives the year in which 
the experiments began, either with the selection of tri- 
