LABORATORY AQUARIUM. 215 
may wish to call it, is only 30-40 microns long. (Less than 
1-500 of an inch. 
Our professor of zoology can obtain and keep vegetative 
euglenae at will, by putting some crumbs of bread in a jar o 
stagnant water. Bacteria and mould will come out only in 
small quantities because it decays in direct sunlight. He ob- 
tained Haematococcus and even the rare stages of conjugation 
and daughter cell formation, by taking debris from a place 
where such were found in the field and adding rain water. 
His laboratory is, however, on the south side of the building 
where he has direct sunlight most of the day. 
Microscopic animals, on the other hand, seem to develop 
better on diffuse sunlight and in large vessels. I have obtain- 
ed some specimens of Zoothamnia, fragania, fairy-shrimps, and 
spongelike animals that were quite rare, or were not reported 
from this part of the country, and they develop in great num- 
ers. Hydras, both the small green species (H. viridis) and 
the larger chlorophylless one (H. fusca) come in great abund- 
ance in late spring and early summer, both in large and med- 
ium sized aquaria and are usually found together, the latter 
disappearing first as its food gives out, the former chloro- 
phyl bearinf remaining for months. 
When water is too alkaline, or contains too much lime in 
solution, a few plants of chara should be introduced into the 
aquarium. The plant is called Stonewort, because of large 
quantities of calcium carbonate present in it. Plants intro- 
duced in summer grow readily and fruit well the oospores 
remain in good condition till germinating in spring. ; 
apwater is used for the aquarium unless it contains too 
much iron. The water must be allowed to run some time be- 
fore filling a jar, as water standing in pipes, especially iron or 
lead pipes, is dangerous. Water contains iron when it leaves 
a brown spot, where it drips constantly. : 
An inch of sand in the bottom of vessel is sometimes bene- 
ficial, when animals are present it is objectionable as they find 
a refuge, then bury themselves and can with difficulty be re- 
moved. Soil is sometimes good but often serves as a hiding 
place for worms like Tubifex, and this might be remembered 
by those who want animal rather than plant forms. When 
soil is taken from the natural habitat of the plant it is an ad- 
vantage, but when taken in larger proportion than one-tenth 
of the contents of the jar, will usually grow more animals than 
plants. 
In transfering algae from the field to the laboratory only 
a very small amount of material should be put in each jar, or 
decay will result rapidly. Though algae appear sometimes in 
