98 



formers in the non-assimilating cells; they produce starch from assimi- 

 lated materials supplied by other parts of the plant." 



It may be stated also that the origin and formation of starch grains 

 as described by this brilliant Alsatian was essentially correct, as later 

 studies of others have shown. At that date the technique which now so 

 clearly brings out the primordia of plastids was unknown. 



In the aleurone layer of the endosperm of Zea Mays, the primordia 

 of the aleurone grains are first recognized as very minute, rounded g]-an- 

 ules which may stain densely and uniformly. As they increase in size, 

 they become globular with a smooth and sharply-defined contour and re- 

 veal a pale or colorless center. They may be represented by making a 

 minute circle with a pencil. As they become older, they increase in size 

 and usually take on a pale yellowish or orange color with the stains used. 



It may be remarked also that the starch grains in the endosperm of 

 Zea originate in a similar manner and from primordia that are indis- 

 tinguishable morphologically from those of the aleurone granules, with 

 the diff^erence that in the case of the leucoplasts the starch inclusion 

 stains blue with gentian violet. 



In addition to the primordia of the plastids mentioned, other sim- 

 ilar though smaller bodies are present — frequently in very large num- 

 bers in the cells — which do not become either leucoplasts or chloroplasts. 

 To these I have confined the term chondriosome. Such chondriosomes are 

 especially well demonstrated in cells of the liverworts, Anthoceros and 

 Marchantia. 



The conclusion reached is that the primordia of leucoplasts and 

 chloroplasts and the bodies here designated as chondriosomes are per- 

 manent organs of the cell, having the same morphological rank as the 

 nucleus. 



The function of chondriosomes is not known. It is generally con- 

 ceded that they are concerned in certain metabolic activities of the cell. 

 Being definite organs of the cell, they may be regarded also as playing 

 some part in the role of heredity. 



