of Chloroplasts and Leucoplasts. 105 
believe that the rods represent rows of granules closely united, which may 
separate into granules. As to this, I am not thoroughly convinced. While 
the round bodies are much more numerous, yet rods usually occur, and 
some of these rods present a perfectly homogeneous structure, not only here 
but also in the other plants included in this study. 
Deeper in the stem, near the base of the cotyledons, the chloroplasts 
present the form shown in Fig. 11 , a. They are similar in form, being 
a trifle larger. One or two inclusions may be present. The inclusion, or 
inclusions, may be relatively small, occupying one end of the plastid, or 
larger, entirely filling it. Passing now to the outer part of the cortex of the 
stem, the chloroplasts are seen to be much larger, rounded or polygonal, and 
somewhat crowded (Fig. 11, b and c). These full-grown chloroplasts stain 
very densely and present a homogeneous structure, save for the presence of 
one or more inclusions. In the large, polygonal chloroplasts the two or 
more rounded inclusions are either grouped near the middle or at one side, 
or somewhat scattered. The smaller and rounded chloroplasts contain, as 
a rule, but one inclusion located at one side (Fig. it, b). At #, Fig. 11, are 
shown five small rounded bodies which are derived from the small rods and 
granules shown in Fig. 10, namely the chondriosomes. They vary in size 
and in number in different cells. In cells of the enlarging cotyledons, in 
which large intercellular spaces have begun to be formed in the chlorenchyma, 
the cells, rich in large chloroplasts, contain relatively few chondriosomes. 
In the cells of the elongating hypocotyl, and especially those of the cortex, 
the chondriosomes are especially numerous. 
It may be stated here that in none of the objects used in this study 
have I found chloroplasts in the form of the conventional rounded or 
elongated object with a dense body in the middle called a pyrenoid. The 
nearest approach to the conventional chloroplast is seen in Fig. 11, c, which 
shows a large chloroplast in division. In the cortex of the hypocotyl, 
division stages of the large chloroplasts are frequently met with. Deeper in 
the hypocotyl, the leucoplasts or chloroplasts usually present the form of 
Fig. 11, a . Along with these, there are present those that are club-shaped, 
or pear-shaped, or in the form of a hand-mirror. 
Elodea. A study of the stem and young leaves of Elodea canadensis 
was made in order to compare my findings with those of other 
observers. 
Cells of the base of young leaves present an appearance not unlike those 
of certain root cells of Pisum , Adiantum , and Zea, as shown in Figs. 2 and 
15, the large, densely-staining, rod-shaped primordia of the chloroplasts 
being, apart from the nuclei, the most conspicuous objects in the cell. 
Lewitsky gives a good representation in his Figs. I and II ( 2 , 1911 ). 
Some of these bodies are dumb-bell-shaped, as stated by Lewitsky, and are 
undoubtedly undergoing division. Many are also club-shaped. In addition, 
