354 BOTANICAL GAZETTE [MAY 
tively small amount of chlorophyll. The failure of the plants to 
become green cannot be ascribed to a failure of the plastids to 
develop, but rather to an absence of a sufficient amount o 
chlorophyll. 
The striped plants of this strain possess varying amounts of 
green and yellowish green tissue, as already pointed out. To the 
naked eye the boundary between the green and yellowish green 
areas appears to be very sharp, but when viewed with the microscope 
there is seen a region of transition one to several cells in width, in 
which are found plastids showing many intermediate sizes and 
depths of color, even within a single cell. Although the transition 
regions may vary in width, careful search has so far never failed 
to. reveal cells which are in some degree intermediate in character. 
In some cases there is a single transitional cell which may contain 
plastids of many shades of green, whereas in other cases there may 
be a series of several transitional cells in each of which all or nearly all 
of the plastids are of one intermediate shade. Fig. 50 illustrates the 
condition which is most frequently found to occur in transitional 
regions. The cells on the left are characteristic of yellowish green 
tissue, those on the right are typical of green tissue, the ones 
between contain plastids which vary greatly, both in size and in 
intensity of green pigment. In the light of such facts the inappli- 
cability of hypotheses involving a simple sorting out of plastids of 
two completely distinct types by successive cell divisions is clearly 
evident, so far as the color types in the strain of maize under 
consideration are concerned. To this point we shall return. 
Intra-vitam stains and the use of fixing and staining reactions 
commonly employed have as yet given no evidence that the class 
of cell elements described comprise bodies of more than one kind. 
It is hoped that further studies may contribute something to this 
phase of the problem. 
Summarizing, all of the plant types examined have been found 
to be the same as regards the cytoplasmic inclusions of their 
meristematic cells. Minute proplastids of the same size, shape, 
and general appearance have been observed in the living cells of 
all the chlorophyll types of maize studied. Intra-vitam stains 
and the fixing and staining reactions which have been used by other 
