Lutz, Triploid Mutants in Oenot/iera. 4l*> 



certain vegetative characters which strongly resembled certain 

 characters of (). gigas. It is therefore not impossible that such as 

 were identified from the rosette stage only (as for example Mac- 

 D on gal's "gigas" 30 ) which was not more than two months old 

 when observed by de Vries), may have been triploid mutants, 

 instead of 0. gigas. Stomps (21, p. 60) has indicated, as prev- 

 iously stated, that the second and third plants of de Vries' culture 

 (5, Bd. I, p. 231) may have been such. Gates (12, p. 536) had prev- 

 iously suggested that there might be some question as to whether 

 these two forms were the same as the original mutant since "neither 

 of these plants matured". 



With reference to these two mutants de Vries said (5, Bd. I, 

 p. 231) that he succeeded in bringing the first to flower, though 

 too late to ripen seed. He compared this individual with the 

 descendants of the original 1895 mutant, and found that it agreed 

 with them in all essential points. The second of the two remained 

 a rosette and never developed a stem. 



Since the first of these plants came to maturity in 1898, only 

 three years after the recognition of the original mutant, it seems 

 probable that there was no mistake in the identification of this 

 form. The second of the two may have been a triploid mutant. 



After triploid mutants were once definitely recognized in the 

 Cold Spring Harbor cultures in 1908, eight were identified in 1910. 

 This, together with the further fact that Professor de Vries 

 believes they have appeared quite often in the Amsterdam cultures, 

 leads me to believe that they will hereafter be found to occur with 

 comparative frequency. 



It is therefore possible that 0. gigas may have appeared but 

 once or twice, and that triploid mutants may occur much more 

 frequently than tetraploid forms. 



How shall we explain the fact that 0. Lamarckiana^ or a 

 derivative of 0. Lamarckiana (0. lata), when self-pollinated, may 

 produce an offspring with a chromosome number differing from 

 that of its own? 



Gates (11), in discussing the origin of chromosome number in 

 certain forms which had been reported as having 14, 15 and poss- 

 ibly 16 chromosomes respectively, says: 



"Disregarding the possibility that these results might be due 

 to the well-known variation in chromosome numbers in root 

 tips," etc. 



30) Mutations, Variations, and Relationships of the Oenotheras. D. T. Mac- 

 l, A.M. Vail, and G. H. Shu 11. The Carnegie Institutions of Washington, 

 1907, pp. 34. 



