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 



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

 Photograph by Newton Miller 



perform an important serv- 

 ice by eating all manner 

 of slimes and scums and 



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. 



Special interest attaches to 



spawning habits and sea- 

 sons, since knowledge of 



FIG. 148. Different portions of single 

 laying of toads' eggs 



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 



