ON NAIAS GRAMINEA DEL., VAR. DELILEI MAGNUS. 815 
the superior and brag layers which Dr. Magnus mentions on 
p- 51 of his ‘ Beitr No doubt the cells of the convex side of the 
lamina are slightly the smaller, but the pare is not so marked 
they are represented in Plate 252, Maced 1 to 33, which are 
copied from the figures given by Dr. 
There are a on ta on the leaves, 
and no epidermis; but the surface-cells in 
all parts of the plant have intermixed with 
them reddish pink pigment-cells, whic 
become brown with age. They are probably 
resinous, as they are the last to decay ; 
similar cells occur in other species of 
tas. 
The central portion of the leaf is 
much thicker than the sides, because at 
central bun 2 fed small-sized cells, sur- 
rounded by a layer of six or eight larger- 
sized cells. on oihor side of this central 
tissue are two intercellular cavities, which 
Fia. 63, greatly exceed i . sae the cells which bound 
is anne ive figs. 60 to 65). 
a een ee pp. 51 and 52, Mag- 
ecg | nus Aceesyek Naias graminea as possessing 
Ne, bast-cells in certain fixed positions in the 
leaf, namely, close to the margin, and im-. 
— tely above and below the central 
bundle on the upper and lo eacahites of the leaf (see figs. 81 to 88 
on Plate 252). These haat. poeils I cannot discover, after Rati iey 
search, in any portion of the Reddish plants; but as 
Magnus se (p. 52) that nig specimens soothnchedl 
by Ehrenberg, and Cairo ns collected by 
Schweinfurth, are have diss hae ‘elle wanting, it is 
clear that the Reddish plant corresponds in this par 
ticular with the plants from Lower Egypt. 
On the other hand, the plant from the Italian se 
tions possesses bast-cells. I found them clearly marked 
in specimens in my herbarium collected by Signor 
Malinverni, ‘‘In stagnis fossis et oryzetis circa Quinto 
Vercellensis ditionis pago ewstate 1875”; the accom- 
panying figure a been drawn gale the leaf of one of 
wos plants (fig. 66). 
The line of ‘ibriform cells is _ central one of the 
three series which I have drawn; it is most clearly 
apparent when viewed as a transparent object, from the 
circumstance that its cells do not contain chlorophyll, 
and hence it is visible as a —— colourless line 
in the midst of green tissu 
An isolated bast-cell is ‘ave in fig. 84 on Plate 252, 
and their position in the leaf is shown in figs. 81 to 83 
Fra. 65. 
WHEL: 
SES CTI ig oo 
“ ae / Je: 
ye, 
fe 
ELH ke 
ee BEE Sh ae A x 
.** one . r: 
EL: 
al a 
re 
QT 
