FROGS. 



37 



against the species as a desirable frog for cultural purj^oses ; and other 

 favorable factors must counterbalance if the species is to be kept in 

 the preferred list. If, in nature, two years are required for the bull- 

 frog to pass through the tadpole stage and five or six years more to 

 reach a length of 6 inches, in order to make its cultivation worth 

 while, the dangers and enemies to which it is subjected during those 

 seven or eight years must be overcome or reduced, or else the 

 numbers of bullfrogs must be increased by careful handling to 

 allow for the great Tosses in the course of their growth. Through 

 many years the growth of our food fishes has been observed at our 

 numerous fish hatcheries, but there is next to nothing in the litera- 

 ture of this country concerning the growth of frogs. Some authors 

 have assumed that if, just previous to hil^ernation in the fall or at 

 the outcoming in the spring, the collector found three or four groups 

 of different sizes, these groups had been hatched in as manj^ succeed- 

 ing years. There are, however, great variations. A species which 

 laid from May to August might, in the following August, include 

 some frogs 1 J of a year old and some 1 year old. For growth studies 

 it is imperative that not only the average and range of transforma- 

 tion size, but also the time of transformation, ])c know^i; for exam- 

 ple, a small frog little beyond the transformation size if found in 

 May must be almost a year old, because rarely, if ever, does any 

 frog transform earlier than June. The results which the writer 

 presents in the following table are merely tentative conclusions based 

 only on measurements of frogs of all sizes collected at random over a 

 period of 10 years. 



Estimated Sizes, Range, and Average of Certain Frogs at Yearly Intervals 

 OF Growth, Shown in Inches. 



In most of these forms the frog reaches the breeding condition in 

 four years, and in the case of the pickerel frog, leopard frog, and 

 green frog some individuals may possibly breed when 3 years old. 

 The bullfrogs which reach 7 or 8 inches in length must require 

 seven or eight years for such a growth. In all the forms, a growth 

 of an inch a year is unusual, the normal rate being from 0.35 to 0.75 

 of an inch a year. The wood frog reaches maturity in four years, 

 and the tree toad in three years. In both, the rate of growth is 

 apparently about 0.35 inch a year. 



FOOD. 



The food problem is one of the crucial questions in the feasibility 

 of frog culture. No very systematic seasonal study of the food of 



