Tricot ylous Races Do Not Arise by Selection. 393 
the garden or in the field, which give rise to no more than 
occasional aberrant forms amongst about 10,000 seed- 
lings, as a rule strongly suggest the existence of such 
half races. 
5. TRICOTYLOUS INTERMEDIATE RACES DO NOT 
ARISE BY SELECTION. 
In the first part of the first volume I brought to- 
gether a long series of facts from botanical and horti- 
cultural and, most important of all, from agricultural 
literature, which afforded sufficient proof that specific 
characters do not arise by selection. 
Applied to tricotyly, the truth of this generalization 
is demonstrated by the results of the experiments de- 
scribed in the foregoing section (4) and summarized 
in the table on the preceding page. This result is in com- 
plete agreement with my experience in regard to the 
origin of species and constant races in other cases. In 
contrast to these the so-called improved races of the 
agriculturists which have arisen by artificial and re- 
peated selection are constant only to a small extent (VoN 
RUMKER). On the other hand the so-called heritable 
or constant races do not arise by selection, with however 
much acumen and perseverance it may be prosecuted. 1 
The distinguishing terms are, I admit, not very practical 
and open to much criticism. The two kinds of races 
which they indicate are, however, absolutely distinct 
things, among wild plants as well as among cultivated 
species; but, unfortunately, if we only have a single in- 
dividual before us we cannot, as a rule, determine to 
which of the two types it belongs. Only its progeny can 
decide, and even this, often not until after the lapse of 
1 See Vol. I, p. 106. 
