AMPHIBIA 



315 



these data will enable a community to give effective protec- 

 tion to valuable species. Frogs and toads proclaim this sea- 

 son, each species with its own peculiar note, from the earliest 

 shrill whistles of the spring peepers, and the croaks, clucks, 

 trills, and warbles of the frogs, toads, and tree frogs, to the 

 bass-viol br-wwns and jug-o-rums of the bullfrogs in late 

 June and early July. The eggs are most interesting forms 

 with which to follow embryological development, and their 

 numbers indicate possi- 

 bilities of increasing val- 

 uable species, when we 

 learn to provide favor- 

 able conditions. The 

 toads' eggs are found in 

 strings ; the green frogs' 

 and bullfrogs', in loose, 

 floating films ; the wood 

 frogs', leopard frogs', and 

 pickerel frogs', in globu- 

 lar masses of jelly; and 

 the peepers', single or in 

 small clusters. Observa- 

 tions by the class may yield a table for local species some- 

 what like the one shown on the following page. 



The feeding test. Amphibia afford most convenient ani- 

 mals with which to study foods and feeding habits. Imitate 

 natural habitats in the arrangement of terraria and aquaria 

 moist earth, moss, or sod for toads, wood frogs, and land 

 salamanders, with a forked branch and a small pool for tree 

 frogs, and a larger pool, with a bank of moss at one end, for 

 aquatic frogs and salamanders. Then, for the tests, introduce 

 all sorts of insects, spiders, millepeds, crustaceans, slugs, and 

 worms, counting the numbers and kinds eaten. No single 

 laboratory exercise shows so convincingly the value of the 



FIG. 149. Toad tadpoles as scavengers, eat- 

 ing dead pout at margin of pond 

 Photograph by Newton Miller 



