1922] RANDOLPH—MAIZE 363 
living cells, which react positively to Janus green, and which, by 
their solubilities and staining reactions, resemble phospholipins 
and, to a lesser extent, albumins.”’ 
Noteworthy in this connection are the statements made by 
Morrier (50) as a result of his studies on the origin of plastids. 
In his first contribution on this subject leucoplasts and chloroplasts 
were shown to be derived from minute “plastid primordia.” 
Other minute bodies present in all cells but not developing into 
plastids were referred to as chondriosomes. In a more recent 
paper (51), in which the development of protein bodies (aleurone 
grains) from minute primordia is reported in the endosperm cells 
of Zea Mays and other plants, emphasis is no longer placed upon 
this distinction between primordia and chondriosomes. It is stated 
that the latter, because of their obscure réle, were previously 
called chondriosomes mainly for convenience. In view of the 
fact that the terms mitochondria and chondriosome have been so 
loosely applied to plastid primordia and many other cytoplasmic 
inclusions as well, Morrrer does not use these terms in his most 
recent description, and even suggests that much ambiguity might 
be avoided by dropping the terms entirely. 
The present writer has also felt that much confusion might 
result from the use of the term chondriosome in his description. 
In the material studied there appears to be but one class of cyto- 
plasmic granules, as already stated, these granules representing 
the early stages in the development of plastids. In order to avoid 
any implication as to the ultimate nature of these bodies and their 
relation to other cytoplasmic inclusions described by various 
workers, they have been designated in the present paper by the 
term proplastid. Whether or not the proplastid is a chondriosome 
is a question which can be answered only when the histochemical 
nature and developmental history of cytoplasmic inclusions have 
become better known, and when a definite and uniform terminology 
has been settled upon. The proplastids can be readily observed 
in the living cells. They are clearly visible in the cells of the 
promeristematic tissue of young stems and embryonic leaves, and 
their activities in these tells and their subsequent behavior in older 
cells have been closely followed through all stages of their develop- 
