126 THE AMERICAN WATER WEED. 
our district, having, through drainage and other causes, quite 
recently disappeared from several localities where it formerly 
grew. It has rigid, dark green aloe-like leaves, and grows on 
Bye Potts of lakes and ponds, rising and floating only when 
in flower. 
ANACHARIS ALSINASTRUM (see fig. 1,) is very distinct in 
appearance from either of the two plants previously named ; and 
is so, in fact, from any other British plant. It has long, slender, 
round stems, branching at irregular distant intervals, green 
when young, becoming brown with age. The stems vary from 
a few inches to three or four feet in length, but seldom exceed 
one-eighth of an inch in diameter; and they bear small oval 
pellucid dark green leaves in whorls of three or four at close 
intervals. Long, thin, simple unbranched roots, which either 
penetrate the mud or hang down in the water, are also developed 
at irregular distant intervals. The stem is readily broken at the 
nodes, and each node possesses the power of reproducing the 
plant under favourable circumstances; see fig. 5, which shows 
how slight is the connection of the cellular nodal tissue. 
Thin vertical sections of the older brownish stems in winter 
form very beautiful and most interesting studies in vegetable 
morphology and physiology (see fig. 5.) The stem is strengthened 
by a central axis of fibrovascular tissue, which shows in a very 
clear manner the characteristic peculiarities of such tissue in 
aquatic plants. Some of the vessels of this axial cylinder are 
marked with very faint spirals, but these are never definite, and 
the wood cells are never thickened or lignified. At the nodes 
these cells are-much smaller, and produced inwardly, thereby 
constricting at that point the central air cavity. Strands of 
these cells bend outwardly and form connections between the 
midribs (the only nerves) of the leaves and the axial cylinder 
(see fig. 5, 7.7.) This central axis is bounded by large loose 
cellular tissue, with frequent /acune or air passages. These 
large cells are thin-walled, and their protoplasm contains chloro- 
phyll granules, which in winter are wholly or partially replaced 
by starch granules, forming a reserve store of nourishment to 
be drawn upon by the plant in its next year’s growth. These 
starch-containing cells are still lined with active protoplasm, 
which moves within them in varied manner, carrying the starch 
granules along with it. Those who are familiar with the 
appearance presented by starch when viewed with polarised 
light will readily imagine what a remarkable sight such a 
phenomenon presents. As a rule, cells which contain stored 
starch in any quantity are devoid of active protoplasm; but these 
stem cells of Anacharis are an exception, and thin sections well 
shown form one of the most attractive microscopic objects it is 
possible to conceive. Sometimes the granules will for a time 
gyrate regularly within the cell, and then start off at a tangent 
and follow each other in single file through most intricate paths, 
