* 
10 ON LEMNACE/E AND THE RAPHIDIAN CHARACTER. 
Waterfowl and Water-Voles ; and I have elsewhere described the boun- 
tiful provision of its starch and calcareous raphides for a suitable ad- 
junct to the food of growing animals. Indeed, to me, a Duckweed- 
patch always appears delightful from its very utility, both in this way 
- and as a procreant cradle of those beautiful and mysterious organisms 
which live and move and have their being on the boundaries of the 
two great kingdoms of organized nature. In short, a Duckweed-patch 
is not only the home of many happy families, full of life and enjoyment, 
but it provides either nutriment or shelter, in one shape or other, to 
many creations, from Mammalia down to the Protozoa and Protophyta ; 
and is truly a prolific and provident field, with a little world of its own, 
eminently valuable and useful, although its complete history yet re- 
mains unwritten. 
Lemna trisulca.—The late Dr. Lindley and other eminent botanists 
denied that there is an epidermis on plants which live habitually under 
water. Whether this Lemna be always thus totally immersed might 
admit of question, though it is fairly described, in * English Botany, 
as having its “fronds submerged." In the same great work we find 
only this plant under Sfaurogeton, a section of which one of the cha- 
racters there given is “epidermis absent ;" and this, no doubt, accord- 
ing to the common view, which nevertheless needs further inquiry. 
I have often found an epidermis on parts of plants which are always 
covered by water; so,it would seem, have other botanists, for Schnetz- 
ler, in his memoir on Ufricuíarie, remarks that “in entirely sub- 
merged aquatic plants the leaves are destitute of stomata, and absorp- 
tion and exhalation take place through the whole surface of the epi- 
blema.” But now we are only concerned with Lemnacee, ou both 
sides of the fronds of which au epidermis is commonly present, as may 
be well seen in LZ. minor. And L. trisulea is thus invested with a 
distinct but very delicate and transparent epidermis, which resembles 
the same tissue on the other species of the genus, but wanting the 
stomata which belong to their upper surface.* The margins of the 
* Whilst these sheets are in the press, our attention has been directed to 
Dr. Hegelmaier’s — pu — monograph ‘ Die Lemnaceen,’ which con- 
tio A 
escrij and nu s figures of the structure of all the species 
of the Order far e. “fe. 8, the epidermis of an aérial fro 
(luftspross) of L. trisulca is fin with a stomate. The term epidermis is, 
by some botanists, uctus to its pires condition when provided with sto- 
mata, the thin mem iiia, P subte "ege and Vds qim organs being 
