1922] RANDOLPH—MAIZE 357 
The cases in which the inheritance of plastid characters is non- 
Mendelian present a very complex problem. Added significance is 
here attached to the plastids, and workers are led to assume that 
the plastids themselves in the main are responsible for the inherit- 
ance of the characters which are manifested in them. . As in the 
case of the Mendelian plastid characters, this assumption involves 
the question of the origin and permanence of the plastids, to be 
discussed later. The cases of non-Mendelian inheritance of 
chlorophyll variation have been classified as (1) maternal and (2) 
biparental. 
Attention has already been called in the introduction to the 
well known cases of maternal inheritance reported by Bavr, 
CORRENS, and GREGORY, as well as to that found in maize by 
ANDERSON, whose results have not yet been published. CoRRENS 
assumes that in Mirabilis the absence of chlorophyll is due to a 
cytoplasmic disease which in some way affects the plastids. Two 
kinds of plastids are said to be present, green and colorless ones, 
whose segregation during the divisions of the somatic cells is 
assumed to explain the presence of ‘‘checkered” leaves, as well as 
the complete absence of color in entire leaves and branches. BAUR 
offers a somewhat different explanation for similar cases. He 
believes that there are two kinds of plastids, diseased and normal 
ones, present in the mature leaf tissue, both being permanent cell 
organs with a definite individuality. The primordia of the two 
kinds of plastids are supposed to be transmitted from one generation 
to the next through the cytoplasm of the egg. A somatic segrega- 
tion of these primordia to different cells during the growth of the 
plant accounts for the green and white areas of the mature plant. 
The hypothetical nature of this explanation is to be admitted, 
inasmuch as different kinds of primordia have not been demon- 
strated in these plants, from which it follows that the postulated 
segregation has not been observed. An examination of the meso- 
phyll cells of plants produced by the maternal inheritance strain 
in maize fails to lend support to either of these theories. The 
development of the plastids from granular proplastids has been 
traced carefully in the living cells, and the condition of the plastids 
in the leaf tissue of the seedlings and mature plants has been 
