96 BOTANICAL GAZETTE [January 



plant lacks that determiner, it would not be an unheard-of thing for a cross 

 between the two to show a mosaic (particulate inheritance). But for pure 

 green and pure white branches to form and breed true sexually would involve 

 somatic segregation. Such an explanation is hard to accept, since we have been 

 confident not only that no general reduction division ever takes place in somatic 

 tissue, but also that segregation in individual pairs of chromosomes or parts of 

 chromosomes is impossible elsewhere than at spore formation. We might 

 accept such a possibility for very rare monstrosities, but the case in hand seems 

 to be a matter of fairly regular behavior. Mutation might also account for 

 these results, but this too could hardly be expected to take place with such 

 regularity. 



The other explanation seemed much more reasonable to Baur, but that 

 too he acknowledged to be unorthodox. He assumed that this was not a 

 matter of chromosomes but of plastids, and of course somatic segregation of 

 green and white plastids is quite reasonable. If this mechanism be the true 

 one, however, one must also grant that plastid initials are contributed by the 

 male parent. This last is quite unorthodox and seems flatly contradictory of 

 CoRRENs' ideas, for if enough cytoplasm is contributed by the male to intro- 

 duce plastid initials, why should it not also contribute the diseased condition 

 of CoRRENs' albomaculata ? 



Ikeno,s working on variegated races of Capsicum, confirms Baur's 

 quaUtative results, and makes the case stiU stronger by uncovering some very 

 significant quantitative features. "The offspring arising from the hybridiza- 

 tion between a variegated and a green plant in either of two reciprocal ways 

 contain a relatively far larger number of slightly variegated (less white) plants 

 than those arising from the self-fertilization of the same variegated plant." 

 The intensity of variegation may be progressively diminished by repeated 

 crosses with green plants, but not even a single self-colored green has as yet 

 been obtained in that way. Ikeno concludes that the transmission of varie- 

 gation is not through the nucleus, but through the plastids in the cytoplasm; 

 the male contributes cytoplasm and plastids. 



It seems impossible to reconcile this behavior with Correns' maternal 

 inheritance. To assume that plastid initials originate within the nucleus might 

 :smooth over the immediate difficulty, and would carry us into further comphca- 

 tions. A more hopeful suggestion is that the disease which Correns speaks 

 •of attacks only mature chloroplasts and that plastid initials are immune, as 

 well as the cytoplasm around them. The easiest assumption, of course, would 

 ibe to claim that Correns overlooked a case of apogamy. Otherwise we may 

 "be driven to acknowledge that chlorophyll inheritance in angiosperms is 

 governed by at least two mechanisms, which are not only quite different but 

 directly contradictory. — Merle C. Coulter. 



5 Ikeno, S., Studies on the hybrids of Capsicum annuiim. II. On some variegated 

 races. Jour. Genetics 6:201-229. pi. 8. figs, i, 2. 1917. 



