FIELD BOOK OF PONDS AND STREAMS 



bers in certain small ponds and slow streams. Not one can 

 be seen during the day though each morning may show dozens 

 of new egg clusters, but at night they can be easily found with 

 a spotlight. The males deposit spermatophores about half 

 an inch high which look like glass push-pins and hold hundreds 

 of spermatozoa (Fig. 289). The females crawl over these, 

 taking the spermatozoa into the cloacal chamber (Fig. 288), 

 where they are held ready to fertilize the eggs that are 

 always laid during the night or very early in the morning. 

 Each egg is enclosed in an envelope of jelly and the whole 

 cluster is covered by a thick layer of it (Fig, 289). The eggs 

 are larger and further apart than frogs' eggs (PI. XX). 



Life history. — The greenish brown larvae hatch in two or 

 three weeks according to the temperature. They are about 

 half an inch long and have noticeably flattened heads, "bal- 

 ancers, " the stubs of front legs, and a lusty growth of gills 

 (Fig. 286). During their transformation in late fall and 

 simimer the gills stop growing and gradually become absorbed. 



Aquarium and vivarium study. — Amhystoma eggs are so 

 large that they show early stages of development ver>' clearly, 

 much better than frogs' eggs, but like them they grow very 

 rapidly, and in the warm water of an aquarium these early 

 stages are passed through in a few hours. The larvae can be 

 reared in dishes of water stocked with filamentous algae, and 

 later (as their legs develop), fed with small worms (p. 351). 

 Adults can be kept the year round in a damp vivarium and 

 fed on bits of beef or pieces of earthworms. 



Size. — Adults 6 inches long or more. 



Range. — Locally common in east and central North America. 



Tiger, salamander, Ambystoma tigrinum. — Although tiger 

 salamanders are rare in many localities, they are very widely 

 distributed in the United States and their life history is one 

 of the most interesting among salamanders. They are heavily 

 built and their rusty black bodies are covered with blotches 

 of yellow running together in irregular marbling and cross- 



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