THE MICROSCOPE. - 297 
to wander among the leaflets of the aquatic plants, to swim 
in the clearer depths, or to seek their smaller prey nearer the 
surface. Indeed some forms of Rhizopods are only to be taken 
nearer the surface among the plants. Meny kinds are to be 
found in the ooze gently separated from the bottom mud. Car- 
rying home a bottle full of mud and water and nothing else is 
commonly a useless labor. Rather thrust the tin dippper among 
the aquatic weeds, and after several gentle turns and twists to 
loosen the plants and stir up the water about them, transfer the 
dipper full to the bottle, and hope for the best. The majority of 
microscopic animals may be collected in this way better than in 
any other. The method is not restricted to the Infusoria. 
Although most of these little aquatic creatures are voracious 
feeders, and while some flourish in putrid animal macerations, 
the greater number seem to avoid filthy places. A pond con- 
taminated by offal or the refuse of the city’s garbage, will not be 
a good collecting ground, unless the filth is greatly diluted. 
Water that is offensive to the human being’s sense of smell will 
not as arule contain many animals. A few of a certain kind, 
those peculiarly and emphatically scavengers, will be there, but 
the collector will have a better chance for success, at least so far 
as species are concerned, in a sweet, clear-water pool where the 
weeds are profusely growing, where the trees drop their foliage 
in the autumn and shade the surface in the summer; where the 
lilies bloom, and their leaves die and by their decay supply food 
to the invisible animacules in the shallow depths below. 
A pocket lens has been recommended as_ helpful in collecting 
creatures for the microscopical aquarium. Nothing could be 
more useless. With few exceptions they are all invisible to any 
but a comparatively high magnifying power of the compound 
microscope. A pocket lens will not exhibit them. A few are, 
under favorable circumstances, visible to the naked eye, but 
these are very few. The microscopist who desires the little crea- 
_ tures must through experience know the favorable localities in 
his neighborhood, he must collect them aided only by faith and 
a tin dipper, and until he reaches his microscope he can see 
them by the eye of faith alone. Here the pocket lens is a de- 
lusion. 
There is an enemy to the microscopical aquarium entirely 
visible to the unaided vision, when full grown, and it is one that 
