8o4 FRESH-WATER BIOLOGY 



This may be made out of a common pint fruit jar, by inserting 



a funnel through one side of the cover for pouring in the catch, 



and so arranged that the excess water may run off through an 



overflow tube, after passing through a cloth strainer 



made of the same material as the dip net, and which 



is distended and held in place by two narrow wire 



loops soldered to the inner end of the overflow tube. 



■ --___^' . The strainer cloth is made in the form of a bag nearly 



^"D ^ as long as the depth of the jar, with its upper end held 



" in contact with the inner end of the overflow tube by 



a couple of rubber bands. 



In many cases it is recommended that the collected 

 material be allowed to stand in a shallow vessel after 

 reaching the laboratory, when the creeping forms will 



Fig. 1248. Diagram ^ ^' j T j ,.1, 



of strainer jar; aDDcar ou the surfacc of the ooze and slime, and others 



(i) Funnel intake; -^ -t^ 



(3) clotWraiSr'. ^111 collcct about the edges of the vessel, commonly on 

 the side nearest the source of Hght, or the opposite. 



If it is thought desirable, small portions of the ooze and slime 

 may be examined under the low power of the compound micro- 

 scope. Even the creeping Cyprididae are easier to find than the 

 Cytheridae, such as Limnicythere, as they are more active and 

 readily gather about the edges of any shallow vessel. 



No satisfactory work in identification can be accomplished in 

 most cases until the body with its appendages is removed from the 

 shell. It is not necessary to place the specimens in weak acid so 

 as to decalcify the shell, as a little practice with dissecting needles 

 and microscope will soon enable one to remove the parts from the 

 shell without destroying them. 



After a preliminary examination, place the specimen in a small 

 drop of Farrant's medium or in glycerin. The shell may now be 

 opened with a pair of No. 12 needles, which are mounted in handles, 

 or by the flexible probing needles used by dentists. Free the body 

 from the shell entire, if possible, and afterwards separate the ap- 

 pendages, beginning with the antennae and taking them in order to 

 the furca at the posterior extremity. This is not an especially 

 difficult process, excepting possibly the maxillae, which are com- 

 monly very small and securely joined in place, so that even the 



