Tricofylous 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, w^hich 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.^ 

 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 



^ See Vol. I, p. 106. 



