2416 Journal of Applied Microscopy 



necessary to select some of the stems without roots and mud for examination in 

 the beaker. On looking through the sides of the beaker with the magnifier one 

 is frequently surprised at the variety of species and number of individuals it con- 

 tains. Some species of active habits, e. g., gafnmariis, dap/uiia, leeches, and 

 many insect larvae are quickly seen, if present ; others, e. g,, hydra and bryozoa, 

 contract when the plant is drawn from the water, but soon expand, if the plant 

 has been transferred quickly to the beaker; other species, e. g.^spoiigiHa and the 

 egg masses of snails, are recognized by their form and color. When satisfactory 

 material is found, transfer it to the collecting jars with the water from the beaker. 

 Many species are more abundant on wood that has been in the water for a long 

 time. With the pole and hook draw such water-logged and floating pieces of 

 wood to the shore, pull them out, let the water drain off and then examine for 

 leeches, nymphs of dragon-fly, gammanis, snail's eggs, encrusting masses of 

 spongilla, bryozoa, and larvae of various species of insects either free or enclosed 

 in cocoons. The blade of a pocket knife is used in transferring the free species 

 to the collecting jars, and attached species are removed by cutting a thin shaving 

 of the wood with the animals attached and placing it in the jar. Some species 

 are too active to be captured except by rapidly sweeping the strainer or net 

 through the water at different depths. 



When making collections it is well to visit different localities in which the 

 conditions are quite varied, swamps and ditches affording striking contrasts in 

 fauna and flora with ponds and streams. In making collections do not crowd 

 the jars full of plants Place delicate, rare, or especially fine specimens in bot- 

 tles or jars by themselves. Jars containing hydras should be free from such 

 predatory species as the nymph of dragon-fly. Take the material to the labora- 

 tory and distribute it in battery jars, culture dishes, and other aquaria and expose 

 them to a good light in a south window. After emptying the material into 

 aquaria fill the collecting jars with clear water and examine for specimens of 

 hydra, leech, and other species which attach themselves to the jar. If sheets of 

 window glass are laid loosely over the aquaria, dust and dead flies are kept out 

 and but very little water is needed to replace the loss by evaporation. By this 

 simple and inexpensive method it is possible to keep a wide variety of species alive 

 and in perfect condition for projection work at any time during the winter and 

 early spring as well as during the months when collecting is possible. One of 

 the species which is kept alive through the winter with the greatest difficulty is 

 hydra, but success has attended the use of the above described method for three 

 seasons. The most satisfactory results in growth and budding of the animals 

 during the winter were obtained by placing strong specimens collected late in 

 the fall in a tall and slender battery jar containing a few plants of Chara fragilis 

 growing in a thin layer of pond ODse in the bottom of the jar. To make sure of 

 an abundance of natural food for the hydras a large number of live water-fleas 

 were taken from another aquarium by means of a small strainer and placed in 

 the aquarium with the hydras. The jar was kept in a south window in a room 

 which was allowed to cool off during the night and which became so cold on two 

 or three occasions that ice an inch thick formed on the water of the jar. The 

 jar was not moved, but was warmed up very slowly as the room temperature was 



