4 Campbell . — The Development of the Flower and 
intermediate in character between the very long-styled basal 
flowers and the very short-styled flowers near the apex, 
in which the stigma is nearly or quite sessile. 
In the axils of all the foliage-leaves are borne a number of 
the delicate scales ( squamulae intrav agin ales) so characteristic 
of most of the simple aquatic Monocotyledons. 
The histology of the vegetative organs of the plant has 
been worked out very carefully by Hieronymus : but un- 
fortunately only the roots and leaves are fully described, his 
memoir ending abruptly before the description of the stem 
was completed. Numerous beautiful and accurate figures of 
the histology are however given, which make it possible to 
follow out most of the structural details. 
In common with other aquatics, the leaves contain large 
lacunae, which here are irregularly arranged, and separated 
from one another by single layers of cells. There are 
numerous vascular bundles of the ordinary collateral type. 
The number of these bundles varies much with the size of 
the leaves. Hieronymus 1 states that in the most vigorous 
leaves he studied there were sometimes twenty-one. Of 
these one occupies a nearly median position, near the 
outer side of the leaf, and he considers this to represent 
a midrib. 
The epidermis of the leaves shows the usual elongated cells 
of similar leaves, and stomata are found, characterized by the 
presence of accessory cells not unlike those of many Grasses. 
The authors own observations were based mainly upon 
series of microtome-sections. The material was fixed with 
chromic acid, and, after thorough washing, stained in toto 
with Czokor’s alum-cochineal, and afterwards stained on the 
slide with alcoholic Bismark-brown. For the study of the 
embryo-sac, safranin and haematoxylin were also used to 
some extent as nuclear stains. 
1 Monografi'a de Lilaea, p. 39. 
