example, when the microscope mirror is adjusted for full brightness and the 

 diaphragm is wide open, such transparent creatures as Amoeba can scarcely 

 be distinguished, but with the light much decreased they show plainly. 

 Frequently an additional view, helpful in showing the type of motion, may 

 be obtained by cutting off all light from below and viewing the animals by 

 light thrown directly on them from above. Very weak solutions of iodine 

 or India ink often make locomotive structures of minute organisms more clearly 

 visible under the microscope. 



Collecting methods vary with the season and the kinds of animals sought. 

 For collecting plankton and small aquatic organisms in general, a plankton 

 net is the best piece of equipment. This consists of a cone of silk about 

 two feet long, with the large, open end supported by a wire hoop to which 

 a cord bridle is attached, and with the small opening in the apex of the cone 

 fitted with a small vial, usually of about an eight dram si2;e. In use, ten feet 

 or more of attached cord are unwound, a little water dipped into the net to 

 give it weight, and the net swung out as far as possible into the pond, the 

 cord being allowed to slide freely through the fingers until the end is reached. 

 The net is then pulled slowly but steadily back to the operator and held 

 upright until the water has drained out through the silk, leaving the small 

 organisms concentrated in the vial, from which they can be poured into a 

 larger receiving bottle. The commercial plankton nets are made of silk 

 bolting cloth, various sizes of mesh being available. Although such nets are 

 essential for scientific investigation, the average collector will find a home' 

 made one of ordinary silk much more economical and quite efficient. A swivel 

 such as fishermen use on bait-casting lines may be attached near the bridle 

 to add to the smoothness of operation. 



Other minute organisms that cannot ordinarily be collected with the 

 plankton net may be obtained by gathering up with a pipette some of the 

 brown ooze that often covers the beds of ponds and slow streams. Scrapings 

 from submerged rocks and the under sides of water lily pads are often full 

 of interesting organisms. Bird baths in which the water is kept constant 

 often reveal a surprising fauna and flora, some introduced as windblown dust 

 and some brought in on the feet of birds. 



Larger organisms can be collected with the aid of small, hand, kitchen 

 strainers, which can be obtained with fine or coarse meshes. If the animals are 

 desired in larger quantities, they can be collected from the ponds quite easily 

 with the aid of a bucket. If the collector will wade into a bed of submerged 

 vegetation and grab up a mass of it, transferring it to the bucket witkmt 

 lifting it from the water any more than is necessary, he can then swirl it 

 around, washer-woman fashion, and throw it aside, usually leaving a host of 

 insect larvae, small crustaceans, snails and other animals at the bottom of the 

 bucket. This method usually gives better results than the use of the common 

 dip-net. 



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