iQiSl 



DE VRIES—A MENDELIAN MUTANT 



343 



of high stature, and 25 per cent normal high specimens. This may 



be considered as sufficient proof that the spHtting took place after 



the law of Mendel. 



TABLE IV 



C. DwAurS AMONG THE OFFSPRING OP 0. gigas (A, no. 3) 



The dwarfs were counted in June and July, and the degree of 

 development at this time corresponded with the photographs given 

 in my Gruppenweise Artbildung, p. 316, figs. 115 and 116. At this 

 period they are clearly distinct from the normal specimens and so 

 there was no difficulty in counting them. In some specimens of 

 O. gigas mut. nanella the number of chromosomes has been deter- 

 mined and was found to be the same as in O. gigas itself (28), as 

 was to be expected. Partly on account of this fact, partly in con- 

 sequence of the nearer relationship, the fecundations did not experi- 

 ence the difficulties which are connected with crosses between 

 0. gigas and 0. Lamarckiana mut. nanella. They succeeded fairly 

 well and yielded, as we have seen, relatively large numbers of seeds. 



The Mendelian behavior of the production of dwarfs by means 

 of mutation from O. gigas, moreover, may be proved in another way. 

 If the mutant hybrids of this form are fertilized by the pollen of 

 0. gigas nanella, the expectation will, of course, be the production 

 of 50 per cent of tall specimens and 50 per cent of dwarfs. But, 

 on account of the smaller viabihty of the latter, we should have to 

 be content with somewhat smaller numbers. In 1913, therefore, 

 I crossed some specimens of apparently normal 0. gigas with the 

 pollen of a constant race of 0. gigas nanella, my culture being the 

 third generation derived from a mutant of 19 10 (Gruppenweise 

 Artbildung, pp. 315-316). I was fortunate in choosing, among 



