314 



CIVIC BIOLOGY 



length of 6 or 7 feet. Gigantic species formerly disported in 



the vast swamps that have 

 given us our coal forma- 

 tions. With few exceptions, 

 amphibia deposit their eggs 

 in water, and they all pass 

 through a truly larval stage, 

 the "tadpoles" being fish- 

 like aquatic, legless, and 

 breathing by gills. In ad- 

 dition to insect destruction 

 by the adults, the tadpoles 

 perform an important serv- 

 ice by eating all manner 

 of slimes and scums and 



FIG. 147. Laying of a toad 15,835 eggs 

 Photograph by Newton Miller 



decaying animal and vegetable matter, thus helping to purify 

 surface waters. Aquaria with and without tadpoles may be 

 made to demonstrate this 

 point in a striking manner, 

 and the results may well 

 be applied to the problem 

 of cleansing local park and 

 reservoir waters. 



Natural history of local 

 species. In connection with 

 other outdoor work, collect 

 all the different species 

 of toads, frogs, tree frogs, 

 newts and salamanders, 

 mud puppies, and sirens 

 common to the locality. 



FIG. 148. Different portions of single 

 laying of toads' eggs 



Special interest attaches to 

 spawning habits and sea- 

 sons, since knowledge of 



The top specimen shows the usual arrange- 

 ment; the other two show the crowding 

 and irregular spacing of the eggs in the 

 gelatinous tube near the end of the laying. 

 Photograph by Newton Miller 



