76 



THE AMERICAN NATURALIST 



[VoL.LYI 



ported by Baur (1909), differs from that m Mirahilis in 

 that the spotting is transmitted through the pollen as 

 well as through the egg cells. Spotting appeared in Fi 

 in crosses of white with green without respect to which 

 way the cross was made. As in Mirahilis, wholly white 

 and wholly green, as well as mosaic, branches were ob- 

 served. 



Examples of maternally inherited chlorophyll variega- 

 tion have been investigated by Gregory (1915) in Primula, 

 and by Anderson^ in Zea. The genetic behavior of these 

 materials is quite the same as that of Correns's Mirahilis 

 variegation. The apparent difference in the cytological 

 basis of their behavior, however, must not be overlooked. 



Evidently these plants of Mirahilis, Pelargonium, 

 Primula, and Zea are sectorial chimaeras. Their main 

 interest in connection with this discussion lies in the 

 fact that, starting with a single fertilized egg cell, certain 

 clilorophyll deficiencies are apparently separated out into 

 certain vegetative cells and handed on through definite 

 cell lines, while normal chlorophyll develops in other cell 

 lines, with the result that areas of varjdng extent have 

 one or the other of these characters. In what the 

 mechanism of this segregation consists— if segregation 

 it be— is not in all cases certainly known. It may even 

 be that some cases of variegated chlorophyll are to be re- 

 garded as recurrent variations arising de novo after the 

 manner of somatic mutations but effecting changes in the 

 cytoplasm, or some of its inclusions, rather than in the 

 chromosomes. Baur is inclined to the view that in mosaic 

 plants of Pelargonium deformed chloroplasts are respon- 

 sible for the chlorophyll deficiencies and that these are 

 segregated out by chance in cell division. This view is 

 supported by Gregory, who noted in the young leaves of 

 vai-iegated plants of Primula the existence of nonrial and 

 HihM'Mtic ].lasti.ls in tlio same cells. (%u'vrn< d<.fs not 

 (M.nii.iil liini>.'l! 1.) any pnrticnlar rlruwui nv iiiclnsion of 

 cytnpl.-iMii as tlu" scat ..f llir can.M' of chlon.!)!!'.!! defi- 

 ciency. Kandolph (192:^), from cytological examination 

 of Anderson's striped leaved maize, found that, in the 



3 Unpublished data. 



