LABORATORY AQUARIUM. 209 
written on animal aquaria, the literature on growth of plants, 
refer especially to the microscopic forms,— is indeed 
meagre. The subject is, however, not without the greatest in- 
terest, especially to teachers in high schools and colleges, where 
competent laboratory work is done. No one will question the 
desirability of having live plant material for study, and pick- 
led forms are used only when no other is available. Many of 
the lower forms of plants and animals can only be studied at 
their best in the motile live stage, and the reason students 
often carry away from the laboratory false notions is because 
the living moving plant is seldom seen or at least not as often 
as might be if the teacher realized that with a little extra ef- 
ort, a marvelous interest could be stimulated in the student, 
with living plants. Much trouble is anticipated by the teacher 
in getting live specimens of the lower plants, especially the al- 
gae, but a little acquaintance with the habits of these too little 
known forms, will reveal the fact that much of the anticipated 
trouble is imaginary. 
The plant aquarium is, however, absolutely necessary for a 
consistent study of microscopic plants in laboratory classes. 
Most of the laboratory work in cryptogamic botany has by cus- 
tom or accident, or I know not what other reason, been rele- 
gated to the winter or early spring months, and part of this 
time at least no live specimens can be brought from the field, 
supposing even that the teacher knew just where to get any 
given plants. We must then naturally fall back upon attempts 
at domesticating these lower forms or, to a large extent, fall 
back upon the less satisfactory methods of using pickled ma- 
terial or prepared slides. The best teachers will never for 
habit study give students prepared slides when living material 
is at hand, and in this way, endless explanations about stains 
and other artificial things are avoided. 
y say after a number of years study of the best ways 
of developing plants in the laboratory for class use, that we 
must at the very outset take for granted that the plant aquar- 
ium is as different from the average animal aquarium as their 
respective inhabitants are, and the treatment accorded each 
in order to succeed is entirely different, in fact, in most cases 
quite opposite. Even the vessels that give best results in 
growing or domesticating aquatic animals are entirely differ- 
ent from the vessels that will give good results in growing 
plants. These vessels are invariably of glass, because allow- 
ing better penetration of light, which is, of course, more neces- 
sary to plants than animals. It is pretty well conceded that 
large square vessels made of separate plates of glass, cemented 
together by various mineral cements, are bst adapted for ani- 
