358 BOTANICAL GAZETTE [MAY 
studied thoroughly. A variation, not only in the size of the 
plastids, but in the amount of color pigment as well, is characteristic 
of all the plant types. 
Two distinct kinds of plastids, normal (green) and chlorophyll- 
less ones do not occur in the strains of maize studied; the green 
and colorless plastids observed in these strains do not represent 
distinct categories at all. Theyellowish green plants of the maternal 
inheritance strain produce some plastids which have a diameter 
equal to that of the plastids present in normal green plants, and 
the intensity of the green color may equal that of green plants. 
In general, however, the plastids are slightly smaller and paler in 
color. The striped yellowish green and green plants show no 
sharp segregation of two distinct kinds of plastids. Cells on the 
border line between the two regions contain plastids of varying 
sizes and intensities of color. A single cell in such a region often 
contains plastids showing all degrees of variation found in either 
yellowish green or green areas. Such intermediate conditions are 
prevalent in the transition region between the two kinds of tissue, 
and at no time can there be found two distinct kinds of plastids, 
either in different cells or in the same cell. GREGORY made a study 
of the breeding behavior of a strain of Primula sinensis which 
produced chlorotic plants. The experimental results showed the 
character to be maternal in its inheritance. In chlorotic cells the 
plastids were shown to be pale yellow and smaller than in cells of 
the green tissue, but in any individual cell of mature tissue the 
plastids were found to be all alike. In young actively growing 
cells, however, different kinds of plastids occur in the same cell, 
_ which are similar to the two kinds found in the green and chlorotic 
cells of the mature leaf. GREGORY uses this as evidence that 
both kinds occur together in embryonic tissue, and later become 
segregated to different regions of the plant, and concludes that 
the abnormality is localized in the plastids. There is, however, 
another interpretation to be placed on the variation in the size 
and color of the plastids present in the growing cells of the leaf. 
In maize there can be no doubt that this condition is due to the 
presence of different stages in the development of plastids of one 
kind. The association of plastids showing a great variation in 
