372 Mrs Arber, On Root Development in Stratiotes aloides L. = 
adjacent segments of the sieve-tube. Their horizontal walls bear 
no relation to those of the sieve-tube, showing that they have not 
been derived from the same mother-cell. 
Like those of so many water plants, the roots of Stratiotes im | 
their young stages are green in colour. The chlorophyll grains 
occur chiefly in the cortex, especially in its inner region, and | 
also very richly in the root-tip, both in the root-cap and internal | 
tissues. Starch occurs abundantly in the inner cortex. A small) 
quantity also occurs in the central cylinder, especially in the) 
developing vessels and sieve-tubes. 
. Ill. The Nuclev. 
(i) Observations. 
The young adventitious roots of Stratiotes aloides, while still | 
enclosed in the stem tissue or just emerging from it, show two | 
very marked cytological peculiarities—firstly, that the cells, : 
especially those of the root-cap and cortex, not infrequently ) 
contain more than one nucleus, and secondly, that the nuclei | 
themselves, both in the cortex and the stele, are often bilobed. | 
Multinucleate cells also sometimes occur in the adjacent tissues of | 
the parent stem. Pl. VIII, Fig. 5 shows one of the most extreme « 
cases I have observed, as regards number of nuclei. Here the | 
outer cells of the root-cap of a young root, and also certain cells 
of the stem cortex through which it was dissolving its way, are | 
characterised by numerous nuclei, one cell of the root-cap contain-. | 
ing at least 12. This case is however of minor interest, since the | 
tissues in question may well be held to be in a decadent condition, | 
but in the examples figured in Plate IX, the cells concerned belong } 
to the normal tissues of the leaf, root-cortex and root-stele, which | 
are still undergoing development. In Pl. 1X, Fig. 7 a, cells belong- - 
ing to the root cortex and containing more than one nucleus are ° 
shown, while Pl. 1X, Figs. 6 and 9 a—e represent lobed nuclei and | 
binucleate cells occurring in the xylem parenchyma and other! 
tissues of the central cylinder. Lobed nuclei are notably frequent 
in the cells immediately surrounding the vessels; in Pl. IX, Fig. 6, , 
three cases will be seen in which these xylem parenchyma elements 3 
were binucleate, while in one of these cells (~) each member of the » 
pair of nuclei was itself bilobed. Lobed nuclei and cells with more > 
than one nucleus are not confined to the root and the adjacent stem © 
tissue, but are also to be found, though comparatively rarely, im: 
the meristematic apical region of the stem and in the leaf (Pl. IX, , 
Figs. 8a and 6). In the latter organ they occur more frequently ' 
towards the base, where growth is presumably taking place, than | 
in the upper part where the tissues are mature. It is, however, , 
only in the young root that these nuclear peculiarities become a 
really conspicuous feature. i 
