MIDLAND NATURALIsT. 87 
daily change of water means a daily change of environment, and 
they have no sooner made an attempt to react favorably to their 
surroundings and begun to accomodate themselves when new con- 
ditions are again forced upon them. , Therefore changing more 
than once the medium in which they are, is doing them the great- 
est harm possible, and under the circumstances algae almost in- 
variably die, and disappear very soon, sometimes not to return. 
It is, therefore, just because these plants are so delicate and are 
affected by influences so subtle that we do not yet fully understand 
them, that we must refrain from multiplying the difficulties under 
which they thrive. The fact that most of these plants are nor- 
mally found in stagnant or still water, which nature does not 
change, at least during their lifetime or growing period, is proof 
enough that they grow best in water in the laboratory which most 
resembles their natural habitat. Some algae like Chetophora, 
Batrachospermum and Ulothrix are found in running or dripping 
water in their native abode. Such plants are, however, perma- 
nently transplanted from the field to the laboratory with the great- 
est difficulty. It is almost impossible to preserve live Ulothrix, for 
any length of time, whether put into still or running water after 
collecting. 
In general, plants must be brought from the field to the 
laboratory with conditions as near as possible to those under which 
they are found, and so kept. It is always best, when possible, to 
put into the vessels the very water in which they were obtained. 
Some algae can not stand the shock of being transferred to other 
water in the aquaria. A single change of water is fatal to them. 
Such delicate forms may, however, be obtained and made to grow 
by a method which will bé outlined in the course of this article. 
Algae which can withstand the shock of a single change of 
water from the field to the tap water in the aquaria will present no 
great difficulties in their successful growth. Often it will be found 
that they disappear for the time being. The beginner will conclude 
that they have completely disappeared as the result of bacterial 
action, or death, when they have only gone into some resting stage 
begin over again with another culture. Starting another culture 
is of course a good thing to do, but it is also good to leave the con- 
tents of the jar for a few months, and it will be invariably found 
