of Chloroplasts and Leucoplasts. 107 
if sufficiently stained, as a narrow crescent. The size and staining capacity 
of these starch grains vary in different preparations, depending probably 
upon the condition of nutrition in which the plants were when killed for 
study. 
In the axillary scales of Elodea canadensis plastids are not well 
developed, very few chloroplasts or leucoplasts being present in the pre¬ 
parations. The two kinds of primordia, namely, small granules and rods, 
are very numerous. In certain cells of these axillary scales, some of the 
rod-shaped primordia develop into rather long and smooth rods or rods 
made of rows of small granules, which stain black with haematoxylin, not 
unlike those found in the mucilage hairs of Marchantia (Fig. 5). 
In the meristematic cells of the stem-tip of Elodea , two sorts of 
primordia are present in the homogeneous groundwork of the cytoplasm, 
namely, very minute round bodies and slender rods. The rods are very 
conspicuous in well-stained preparations. As in meristematic cells of other 
plants, they vary in length and thickness, some being robust, and others 
very slender and delicate. Some seem to consist of a row of densely-staining 
granules. The transformation of these rods into chloroplasts and leucoplasts 
has been described in the foregoing. The minute round bodies stain palely 
and have a colourless centre. They may be represented by simply making 
a small circle with a hard pencil. Their periphery seems to be rather firm 
for so small an object, and that fact enables one to detect their presence. 
In older cells of both leaf and stem they are somewhat larger and very 
numerous, and they stain densely and uniformly. They appear now to be 
globules or very short rods of uniform structure ; for many become elongated 
into short rods which may be, as a rule, about two to four times as long as 
thick. In older cells of the leaf with well-developed chloroplasts, these 
granules and short rods lie among the chloroplasts and stain like them. 
Both rods and granules divide by.fission like mature chloroplasts or their 
primordia. As mentioned in an earlier paragraph, both sorts of primordia 
may be seen in fresh cells of young leaves that have been treated with iodine 
in potassium iodide solution. 
Hydrodictyon. Space will permit of only a brief reference to findings 
in this plant. In cells of healthy, growing, though immature, individuals, 
the technique here employed revealed numerous round, or apparently 
globular, bodies remaining densely stained with the haematoxylin when 
other cell contents were colourless as a result of destaining. Since there are 
no individualized chloroplasts in the species in question, and the starch 
formed is clustered about the easily recognized bodies that pass as pyrenoids, 
there is no danger of confusing primordia of plastids with these bodies, 
which, for the time being, may be designated as chondriosomes. They are 
to be seen in the live cells as round, highly refractive bodies. 
A further discussion will be reserved for subsequent publication. 
