354 Mot tier . — On Certain Plastids , with Special Reference to 
makes the sweeping statement that aleurone grains are dried out vacuoles 
in the seed. ‘ During the process of ripening (1910, p. 155 ) the amount 
of protein matter dissolved in the cell -sap gradually increases until the 
fluid becomes of a thick, slimy consistency. In drying, some of the protein 
bodies crystallize and form the well-known crystalloids, while the remaining 
protein hardens into an amorphous mass around them.’ 
De Vries, like the majority of his predecessors, regarded protein 
granules as a separation from the cell-sap as a sort of mother fluid. We 
are not told how the aleurone came to be in the cell-sap or cytoplasm in 
the beginning. 
As stated by Pfeffer and Wakker, aleurone granules appear in the 
endosperm of Ricinus as the seed approaches its mature size, and when the 
seed-coat begins to show a brown colour. A cross-section of the seed at 
this stage, or even a little earlier, shows several stages in the formation of 
the protein bodies. The cells nearer the developing embryo, that is, near 
the central part of the endosperm, and those at the periphery, contain no 
protein granules as these are usually understood. Fig. 6 is intended to 
represent one of these cells, which is' taken from the periphery of the 
endosperm. Those near the centre show a similar structure. It should be 
borne in mind that cells immediately bordering the cavity in which the 
embryo lies may be undergoing dissolution. Such cells show frequently 
one or a few large vacuoles. At the stage of development shown in Fig. 6 , 
the nucleus is centrally placed in a mass of cytoplasm. About this are 
vacuoles varying in size. The vacuoles at this stage contain only cell-sap. 
In the cytoplasm are clearly differentiated many densely staining granules 
and short rods, along with a number of rounded bodies that are larger, and 
which often do not remain stained so densely with the degree of differential 
staining represented by this figure. The larger rounded bodies are doubtless 
the primordia of leucoplasts, while the remainder are the primordia of other 
plastids. 
Freehand sections of fresh or alcoholic endosperm at this stage treated 
with iodine in potassium iodide reveal the presence of small starch grains, 
especially at the periphery and at the inner region of the endosperm near 
the embryo. These starch grains are small, of variable size, and the blue 
coloration is not very marked. This represents the transitory starch 
mentioned by Pfeffer, but it does not appear sufficiently abundant to 
obscure observation. 
In Fig. 11 are shown leucoplasts with their inclusions, taken from the 
peripheral cells of the endosperm, as they appear in the permanent 
preparation made according to the technique employed. They are very 
small and are similar to the leucoplasts found in tissues of other plants, such 
as Zea and Pisam . Some are rounded, while others are in the form of 
a hand-mirror. 
