Gates, Tetraploid Mutants and Chromosome Mechanisms. 14;; 



werden konnen" has ended in failure, because it necessitates assump- 

 tions which the already known cytological facts disprove; though 

 without a knowledge of these facts his hypothesis might have seemed 

 plausible, at least in part. 



N. Heribert-Nilsson (1912, p. 212) also attempts to explain 

 the origin of rubricalyx from rubrinervis in my cultures through 

 the accumulation in one individual, of several independent quantita- 

 tive "factors" for pigmentation. He says, "0. rubricalyx ging 

 allerdings aus einem geselbsteten Individuum hervor, aber Gates 

 erwiihnt, dass er in seinen Kulturen m eh re re rubrinervis-lAmen 

 gehabt hat, und Kreuzung zwischen ihnen kann ja in den vorigen 

 Generationen stattgefunden haben". 



Unfortunately for his theory, I can state the facts more defin- 

 itely than they were given in my publication on the inheritance 

 of pigmentation (1911 b). They are as follows: In 1906 I grew at 

 Woods Hole, Mass., a culture of 45 plants from rubrinervis seeds of 

 de Vries. These were all rubrinervis except two Lamarckiana and 

 one oblonya. A number of the individuals were self-pollinated, and 

 together with rubrinervis cultures from various other sources, 

 making a total of over 1000 plants, were grown at the University 

 of Chicago in 1907. The particular culture in which the rubricalyx 

 individual appeared, contained 112 plants, all typical rubrinervis 

 except the rubricalyx individual and one or two other rosettes 

 which were somewhat aberrant and doubtful. This culture, which 

 alone is concerned in the pedigree of rubrinervis, contained the 

 offspring of four plants (Nos. 96, 98, 119 and 121) which had been 

 selfed in the previous generation. 



These four cultures should have been kept separate, but were 

 thrown together because this made no difference in the experiments 

 I then had in view. The rubricalyx mutant with its new dominant 

 character therefore appeared as one of the 112 offspring of four 

 purely self-pollinated rubrinervis individuals, which were sister plants 

 from a culture Q O. rubrinervis from seeds of de Vries. It there- 

 fore belonged to the second self-pollinated generation from de Vries' 

 seeds, and any hypothetical crossing of pure lines must be relegated 

 to de Vries' cultures. The presence of two Lamarckianas in the 

 original culture may be attributed to mutation or to the entrance 

 of foreign pollen, for I cannot be certain that the seeds is the 

 original packet were guarded seeds. 



Nils so ITS hypothesis is impossible for several other reasons. 

 1) As I showed in the paper above-mentioned (Gates, 191 1 b) from 

 these very cultures, the range of pigmentation in 0. rnbrincrris 

 buds was absolutely continuous, but there was a wide gap bet- 

 ween the extreme plus variation in rubrincrris and the individual 

 mutant (see plate 6 of that paper). 2) The behaviour 



