92 MIDLAND NATURALIST. 
tionately to the size of the jar bacterial decomposition will result. 
The process was also tried with other plants and usually with good 
results. 
Striking results are always obtained with Vaucheria geminata. 
The plant begins to appear late in the fall in its native habitat 
around springs and in pools. At the beginning of winter it has 
usually attained a considerable length of the filaments. The winter 
usually comes on it in the vegetative stage, and in shallow pools 
it is frozen hard in the ice until Spring. Cakes of ice containing 
this plant may be put into cold water and within a few hours after 
melting out be brought into a warm room. Several days later, so 
great an abundance of zoospores will result that they literally 
cover the surface of the aquarium, and can be scooped off in all 
Stages of development for study. If the spores are left they will 
develop into new plants, which in the course of a few weeks will 
begin to develop an abundance of oogonia and antheridia, while 
the older plants will disappear. The plant can then in this way be 
made to produce zoospores any time during the winter season. A 
rather large aquarium serves best, and flowing or running water is 
not necessary, nor any regulation of light as is usually prescribed 
for zoospore production by older methods at other times of the 
year. Vaucheria sessilis will respond as favorably as Vaucheria 
geminata to such treatment but the latter is usually more abundant. 
Vaucheria sericea, a much smaller species than the two preceding 
has also been used with success. 
Diatoms which are usually present in large quantities around 
springs and in pools and ponds can be taken into the warm labora- 
tory in like manner and within a few hours afterwards will show at 
their best their characteristic movements. These plants always 
show their movements best shortly after being brought from colder 
to warmer water, so that in summer even, their motion are 
best demonstrated when brought from cold spring water to -the 
warmer surroundings of the laboratory. 
By a process of treatment not unlike the ‘‘forcing’’ method just 
cited, Hydrodictyon was last winter made to develop in the labora- 
tory when there was freezing weather outside with several feet of 
snow on the ground. A jar in which a small amount of this plant 
was put for preservation during the fall and winter, was put on a 
window shelf just over a radiator where the heat was excessive and 
constantly equal day and night. The great heat brought about a 
