47 
ance afforded by water plants, the purpose of vegetation is to decompose 
the carbonic acid gas thrown off by animals, the carbon being absorbed 
into the substance of plants, and the oxygen set free for animal life. Even 
a growth of confervas, unsightly as it is, is conducive to this. In a large 
Aquarium, a lily may be introduced, planted in a shell or small pot, hidden 
by weeds, but any plant that grows above the water is apt to aid any 
creeping animal to effect his escape. The whorled millfoil is one of th e 
best plants for general use as it prefers still water, and I have succeeded, 
by inserting it late in the fall, in keeping it through the winter in suffi- 
cient quantity to answer all purposes. The goldfish and others of the 
Carp family, nibble at it, and it is probably as essential to their welfare 
as vegetables are to man. Valisneria is a clean, sightly plant and 
answers well as an air provider, besides being one of the few plants 
which afford a microscopic view of the circulation of the sap in the 
leaves. 
There is a pleasure in connection with keeping an Aquarium, that 
to a lover of Nature, adds materially to the charm that attends the 
observation of its inmates, and that is the rambles made to collect 
various specimens of aquatic life. The keen lookout for water snails 
amongst the vegetable growth at the bottom or on the surface of some 
stagnant pool, and the eagerness to get the little scoop net over one, 
perhaps just out of reach, affords a pleasure, equal to, if not surpassing 
that felt by the sportsman beating the bush for game, or the fisherman 
eagerly watching his bait. The health-giving stroll along the bank of 
some tiny streamlet, on the lookout for minnows or larvae or any of the 
varied inmates of its waters, is far different from the monotonous con- 
stitutional, along the dusty highway, of the man who has never read a 
page out of Nature's book of life. The most important principle, per- 
haps, in life, is to have a pursuit, a useful one if possible, and at all 
events an innocent one. The scenes you enjoy, the contemplation to 
which they lead and the exercise attendant on specimen collecting are 
salutary to the body as they are to the mind. I always find a peculiar 
effect in such outings ; they carry me back to early times and feelings, 
and create afresh the hopes and happiness of youthful days. Could we 
all recover anything like that freshness of mind possessed in youth, 
which, like the dew of morning covered all objects, and in which they 
