402 Origin of Each Species Considered Separately. 



dozen flowers on two stems which arose from the axils 

 of its radical leaves. These attained a height of about 

 half a meter. But in spite of all the trouble I took I got 

 no fertile seed from it. 



The third mutant arose in 1900 in the first Lata- 

 family, as already recorded in the genealogical table on 

 p. 285. It is figured in Fig. 85 B. It was planted out in 

 June, grew well, but remained short and did not branch. 

 It bore large flowers and small fruits and was cut off at 

 the end of August to be photographed. 



The fourth mutant (Fig. 85^) arose from a cross 

 between O. rnbrinervis and O. nanella, which was made 

 in 1899. It developed an unbranched stem, which at- 

 tained a length of about half a meter, in its first year, 

 but it did not flower. 



D. THE STERILE SPECIES. 

 § 22. OENOTHERA LATA. 



One of the most difficult questions which the muta- 

 tionist has to answer is that which refers to the nature 

 of the fundamental process, involved in mutation the 

 visible results of which are the peculiarities and char- 

 acters by means of which the new form is distinguished 

 from the parent species. I have already laid stress on 

 the fact, which has not escaped the notice of the best 

 workers in this field, that elementary species are not dis- 

 tinguished from one another by one character only, as 

 varieties are, but by almost all their organs and charac- 

 ters. This is not only true of the elementary species, in 

 a state of nature, which have been described by Jordan^ 

 Gandoger, Thuret, De Bary, Rosen and many others 

 but also of those which have arisen in my cultures. 



