SCALES OF AQUATIC MONOCOTYLEDONS. 233 
The scales are solitary in the axil of each leaf, arising from a 
double row of initial cells and maintaining that thickness through- 
out save at the extreme margins, where they are unilamellar. 
The leaf possesses a relatively massive median vascular bundle, 
and the scale, at first central in position, takes up later an 
oblique position opposite one of the thinner lamell: of the leaf, 
or forks into two wings one on either side of the midrib. Bal- 
four (11) elsewhere describes the existence of az axillary scale, 
and points out that though at first median it attains later a 
lateral position. In the memoir above referred to (10) he says 
* there are two of these (scales) at the insertion of every leaf 
placed one on either side of its base." These two somewhat 
divergent statements may perhaps be reconciled by the scale some- 
times splitting, sometimes remaining entire. 
STRATIOTES. 
The scales in Stratiotes aloides are most variable in number 
owing to their frequent division. As an example, I may give 
the number of scales in the first twenty leaves of the bud in a 
case in which the scales were counted :— 
I= 2: II- 7: III- 7: IV= 9: V= 8: 
VI=10: VII- 7: VUI=7: IX= 9: X=10: 
XI= 9: XII213: XIII-I11: XIV=13: XV=13: 
XVI2 8: XVII=14: XVIII— 9: XIX=12: XX=11. 
The scales appear to arise from a ridge of three or four cells, 
and maintain that thickness for some distance above the point of 
origin (Pl. 6. fig. 13). The main body of the scale is two layers 
in thickness, reduced at the free end to one layer. [The spaces 
between the closely-packed leaves are the abode usually of 
countless numbers of nematode worms. | 
HYDROCHARIS. 
Two or three massive scales appear in each leaf-axil of Hydro- 
charis Morsus-ranc, resembling in appearance those of Stratiotes. 
One peculiarity worthy of note is the early cutinization of the 
basal cells of the scale, which then stand out prominently. As 
cutinization progresses the cell-contents, at first very prominent 
and taking on a deep stain, gradually disappear. In old scales 
the cells are quite empty (Pl. 6. fig. 11). The upper part of the 
scale then drops off, leaving a cutinized ridge only. The cutin 
