95 
of Chloroplcists and Leucoplasts. 
slender, delicate rods vary also in length and thickness. In fact, all of the 
bodies mentioned vary in form and size. Although under lower magnifica¬ 
tion the cells appear as if containing numerous rod-shaped bacteria, the 
rods and granules are very readily distinguished from bacteria, because of 
the uniformity in the size of bacteria and the smooth, clear-cut surface 
of their cell walls. 
Passing back in the root to where the cells of both plerome and cortex 
begin to elongate, it is clearly seen that the larger rod-shaped bodies 
change gradually into those which take on the form of a club- or pear- 
shaped body or that of a hand-mirror (Fig. 3). These are leucoplasts, and 
they contain one or more inclusions or starch grains. The starch grain, 
which represents the glass of the hand-mirror, remains colourless or may 
appear a pale blue, especially when crystal violet is used or if the destaining 
is not carried too far in the iron-alum-haematoxylin preparations. The 
protoplast, which corresponds to the handle of the mirror, stains a jet black 
(Figs. 3 and 4). It is quite evident, therefore, that the larger thick rods 
are the primordia of leucoplasts. A comparison of Figs. 2 and 3 will 
show how these primordia, of whatever length, are changed into leuco¬ 
plasts. The transition takes place as follows : The rod becomes swollen 
or enlarged at one end, where a small and palely-staining starch inclusion 
is forming. The inclusion enlarges, becoming round or oval. The result 
is that the shorter rods become club- or pear-shaped leucoplasts, while the 
more elongated forms take the form of a hand-mirror. I do not regard the 
hand-mirror form as a division stage of the leucoplast. Fig. 3 shows also 
how numerous are the very delicate and slender rods and granules which 
do not become leucoplasts but retain their identity even in older cells of 
the root. These I shall designate as chondriosomes. Fig. 4 illustrates, 
more highly magnified, some of the commoner forms of the larger leuco¬ 
plasts found in older cells of the root that have become greatly elongated. 
In Fig. 4, the leucoplast contains three smaller starch grains. At c 
(Fig. 4) a large, oval starch grain is near the middle of the leucoplast. 
Fig. 4, d, e ) shows other forms of leucoplasts with large starch grains, while 
at a are shown a few of the very much smaller granules and rods that do 
not become leucoplasts. In these same cells are frequently found smaller 
and more rounded leucoplasts containing one or more rounded starch 
grains, as figured at a, Fig. 11, for Pinus. These small leucoplasts are 
more difficult to stain than the larger and may be readily overlooked. In 
addition to the foregoing leucoplasts, the most conspicuous phenomenon in 
all cells of the root-tip is the presence of innumerable round or rod-shaped 
chondriosomes. These bodies do not form the groundwork of the 
cytoplasm, the latter being a much more finely granular or homogenous 
substance. 
Passing now from the root-tip proper to the root-cap, we note that the 
