The Isolation of Tricotylous Intermediate Races. 419 
it is desirable, in connection with what was said in the 
first part of this volume, to consider what we should 
expect to occur in the isolation of such intermediate races 
as may happen to be present. The intermediate race does 
not differ from the ordinaiy types or half races in any 
visible characters, but only in the frequency of tricotylous 
specimens. If the tricotylous individuals are selected for 
culture from crops raised from bought seed, it is by no 
means certain that these and these only belong to the 
intermediate race, if indeed such exists at all. For in 
addition to this, the half race is almost always present, 
and this, as we know, also contains some tricotyls. On 
the other hand the intermediate race always produces 
atavists and usually in considerable numbers. Provided 
therefore that the crop contains an intermediate race, 
some of the dicotyls and some of the tricotyls would be- 
long to it ; but the prospect of obtaining it from the latter 
will obviously be greater than from the former. For this 
reason I select, whenever possible, tricotyls only for trans- 
plantation. All that then remains to be done is to save 
their seeds separately from each plant and to determine 
their hereditary values in the harvest. If any of these 
are especially high they belong to the intermediate race, 
and all the res! are thrown away inasmuch as they in- 
clude the half race and the doubtful cases. Ordinarily 
the race is by this time perfectly pure and can be improved 
by selection on the ordinary lines. As a rule, the means 
of the curves describing my intermediate races, lie be- 
tween 50 and 60%, and can be brought as high as 80 to 
90% by selection in occasional individuals. 
In contradistinction to the unsuccessful experiments 
described in the previous section there can be no doubt 
in these successful cases that we are not dealing with the 
