96 
Mot tier.—Chondriosomes and the Primordia 
rods become fewer, but there seems to be little or no falling off in the 
number of granules. Fig. i represents a cell from near the end of the root- 
cap, in which rounded starch grains are present in the distal end of the 
cell. The most conspicuous objects in the cytoplasm, even when examined 
with the ordinary high powers of dry lenses, are the numerous chondrio¬ 
somes in the form of densely-staining granules, rows of granules, and rods. 
These objects, so numerous here as elsewhere, far exceed the number of 
starch grains that could be contained in any cell of the root-cap, and the 
conclusion is that they are not identical with leucoplasts. While it is not 
possible to distinguish between the primordia of leucoplasts and the rods 
and granules that do not become leucoplasts, I have come to the conclusion, 
from the presence and behaviour of all these bodies in both young and 
older cells, that the primordia of leucoplasts are not the same as these other 
objects. This conclusion is borne out in the case of all other plants to be 
noted below, in which it will be shown that the primordia of chloroplasts 
are identical with those of leucoplasts and that it is probably better to confine 
the name chondriosome to the objects that do not give rise either to leuco¬ 
plasts or to chloroplasts. Both chondriosomes and primordia of leucoplasts 
multiply by transverse division or constriction. 
The rounded starch grains of the root-cap reveal the plastid as 
a narrow, darkly-staining crescentic or rounded body at one side, although 
the plastid doubtless surrounds the whole starch inclusion. These starch 
grains were developed from the smaller rounded or rod-shaped plastids. 
Lewitsky ( 1910 ) figures a cell from the root-cap of Asparagus officinalis 
(his Fig. 18) in which similar starch grains are shown, but these bodies are 
designated in the description of the figure ( 1910 , p. 546) as ‘ Statoblasten’. 
In the drawing he does not show the plastid. While some of the leuco¬ 
plasts in the root-cap and in other parts of the root, as in the cortex, are 
derived from rounded primordia, yet the transition of the short rod through 
the club- and pear-shaped forms is easily observed. 
In the elongating cells of the vascular cylinder of the root, the 
primordia of leucoplasts are apparently more numerous and longer than in 
cells of the cortex. All of the primordia do not develop starch inclusions ; 
those that do not become long and frequently thread-like. They finally 
undergo disorganization in older elements. In the cortex of the root 
the primordia seem to be generally shorter than those of the central 
cylinder. 
Zea Mays. As a second phanerogamic root-tip, that of Zea was 
chosen. 
In the meristematic cells of the tip, including those of the root-cap, 
or calyptrogen, are numerous densely-staining granules and rods some¬ 
what evenly distributed in the groundwork of the cytoplasm. These bodies 
are smaller than in the root of Pisum. The granules are by far the more 
