1922] RANDOLPH—MAIZE 343 
time, even in a water mount. Thus it was found that bits of 
embryonic (meristematic) tissue will remain living and apparently 
in an entirely normal condition for 24-36 hours in.an isotonic 
solution of cane sugar. In most cases, however, observations were 
made immediately after making the mounts in order to avoid the 
possibilty of any modification of the cell contents. Intra-vitam 
stains, such as neutral red, Cresyl blue, Janus green B, etc., have 
been used, but unexpectedly proved to be of relatively little value. 
Various methods of fixation and staining were used, including 
those of BENDA, REGAuD, Cuampy, LAGUESSE, BENSLEy, and other 
special methods which have been reported as being useful in such 
studies. 
Description 
The chlorophyll types here described do not include all the 
known cases of chlorophyll abnormality in maize, but have been 
selected as representative of certain distinct categories, illustrating 
markedly different kinds of behavior, both in development and in 
inheritance. These types are discussed in genetical literature as 
“normal green,”’ “Mendelian white,” and “Mendelian virescent.”’ 
The ‘‘maternal inheritance strain,’”’ discovered by ANDERSON, has 
not yet been described in the literature. 
The development of plastids may readily be followed in the 
meristematic and mesophyll tissues of young rapidly growing 
seedlings. In the growth stages immediately following the germina- 
tion of the seeds, leaf tissue is being formed through the activity of 
the apical stem meristem, and the embryonic leaves thus formed 
are increasing rapidly in size through an active division of the cells 
making up the leaf meristem and through a division and growth 
of the cells throughout the leaf tissue. The meristematic tissues 
during these and later stages furnish very favorable material for 
a study of the cytoplasmic inclusions of the living cells. Since 
it has been found that the cytoplasmic inclusions of the epidermal 
cells, as well as those of the vascular system, differ markedly 
from those of the mesophyll cells in mature leaf tissue, the study 
of plastid development has been limited to the regions from which 
mesophyll cells are derived. 
