38 FROGS. 



our frogs has ever been undertaken and successfully completed. The 

 toad has been quite thoroughly studied throughout its feeding sea- 

 son.*^ The best food investigation of any of our frogs (Rana pijiens) 

 covers a very short feeding period from August 8 to 22,* while the 

 food of the bullfrog has aroused interest and some attention because 

 of some of its bizarre tendencies. As a consequence, the food of the 

 tadpoles, transformed frogs, and adults of our commoner species 

 can not be spoken of as positively as would become scientific par- 

 lance. A summary of what has appeared will have to suffice until 

 comparative studies which are in progress are forthcoming. 



FOOD OF TADPOLES. 



In the earlier days armchair scientists held that the food of a tad- 

 pole had to be almost or quite wholly vegetable in nature, because 

 of the elongate intestine the creature possessed; but even casual 

 observers have noted with what avidity tadpoles assemble around a 

 dead fish. The taxidermist knows very well to what a bone-clean 

 condition tadpoles reduce carcasses of mammals, birds, or cold-blooded 

 vertebrates. Several experimenters in frog culture have maintained 

 that they could raise tadpoles on dressed submerged fish or on liver, 

 a well-known fish food. These animal tendencies in the diet of an 

 apparent vegetarian extend even to the devouring of their own kind 

 under stress of unusual circumstances. It must, however, be remem- 

 bered that most of this animal food, if not all of it, is dead and immo- 

 bile. Seldom do they prey on larger aquatic animals or even on the 

 smaller forms, unless these incidentally occur in the food stream which 

 is mainly vegetable in character. Their animal-feeding proclivities 

 are maiiily those of scavengers, and it is therefore hardly correct to 

 call them carnivorous or omnivorous, as has been done by some. 

 Up to the present time there has been no serious extended examina- 

 tion of the food of tadpoles, because of the enormity of the task and 

 on account of the previous uncertainty of the identification of the 

 frog species to which they belonged. 



FOOD OF TRANSITION STAGES. 



This period when the tadpole changes to a small frog is a critical 

 time in the life histor}^ of any individual frog and is in many ways 

 the most important point of attention for the frog culturist. Tlie 

 creature makes a complete change of form, becomes truly carnivo- 

 rous, spends some of its life on the banks or in the fields, and there- 

 fore can not be expected to adjust itself in an instant to a new exist- 

 ence. Dr. Philip A. Munz, who is studying the food of transforming 

 and transformed frogs, presents the following preliminary and pro- 

 visional summary from his examinations: 



Thus far a fairly representative series of each of the following species of Rana has 

 been studied: R. catesbeiana, the bullfrog; R. damitans, the green frog; R. sylvatica, 

 the wood frog; and R. palustris, the pickerel frog. In each species the same general 

 tendencies are evident: 



a Kirkland, A. H.: The habits, food and economic value of the American toad. Hatch Experiment 

 Station of the Massachusetts Agricultural College, Bulletin 46, A] ail, 1897, Amherst, Mass.; also, Usefulness 

 of the American toad, U. S. Department of Agriculture, Farmers' BuUetin No. 196. Washington, 1904. 



Garman, H.: Kentucky Experiment Station Bulletin No. 91. 1901. 



Hodge, C. P.: Nature study leaflet. Worcester, Mass., 1898. 



b Drake, Carl J.: The food of Rana pipicns Schreber. Ohio Naturalist, March, 1914, Vol. XIV, No. 5, pp. 

 257-269, Columbus, 



