290 Fortieth Annual Meeting 



cover an area of 4 or 5 feet on the surface of the water. 

 These are usually found in a clear space of pure water. 

 The eggs are much smaller than those of the leopard or 

 green frog and, of course, will run in larger numbers per 

 individual. 



Of the smaller species we have found it possible some- 

 times to produce a few frogs the same year the eggs are 

 cast. This does not apply to the common bullfrog, however. 

 The eggs of this species cast in the early summer will not 

 produce a frog until a year from that time. At the latter 

 end of the first summer the tadpoles are very large, and a 

 great many of them will develop hind legs. Then they 

 seem to remain stationary until the water temperature has 

 reached the summer heat of the following year, when the 

 development into a perfect frog takes place in about 

 sixty days. 



It is in the second year of the tadpole's life that we find 

 our greatest trouble. To begin with, we have insect life to 

 contend with, such as the larvse of the Dysticus, or water 

 beetle, which are very destructive. When we have numbers 

 of tadpoles confined in small ponds, large quantities of food 

 must be furnished. As a rule we use fish entirely as a food 

 at the Crawford Station. If the ponds are not looked after 

 carefully and are allowed to become at all foul they will 

 attract the water beetle, which will produce its larvae in large 

 numbers. Fish-eating birds are also a great annoyance. 



The precarious stage in the tadpole's life, I find, is just 

 at the breaking through of the forward legs and the chang- 

 ing of the head to the frog shape. The thinning of the 

 skin to allow the legs to break through seems to weaken 

 the vitality of the tadpole to such an extent that we often 

 find them dead with only one front leg through and the 

 other but partly out. Again we find them dead with all 

 four legs, but the mouth still of the same size as when they 

 were tadpoles. 



As our tadpoles develop into frogs we gradually lower 

 the water in the ponds until we have no more than two 



