358 THE BIOLOGY OF THE FROG CHAP, xix 



emotional feelings. While there is often rivalry among 

 them for the possession of food, their struggles are peace- 

 able and betray no ill temper. The " angry and envious 

 glances " with which, according to Knauer, toads regard one 

 of their number which is fortunate enough to seize a worm 

 for which they are all struggling, are more matters of sub- 

 jective interpretation on the part of the observer than any 

 real emotional expression on the part of the animals. 

 How the countenance of the toad is modified to express an 

 angry glance we are not informed. 



Of sympathy or affection for its kind the frog or the toad 

 shows no trace. Care for offspring is almost of necessity 

 absent owing to the methods employed in reproduction, 

 since the young shift for themselves in entire independence 

 of their parents. The formation of groups in hibernation 

 is doubtless brought about either by the animals happening 

 to get into the same nooks, or through the tendency to seek 

 the slight degree of warmth afforded by each other's bodies. 

 The frog and the toad are pure egoists. Their only acts 

 which have any reference to other members of their species 

 are those prompted by the blind impulses to reproduction 

 which nature has implanted in these animals in the in- 

 terests of their posterity. 



REFERENCES 



Abbott, C. C. The Intelligence of Batrachians. Science, Vol. 3, 

 pp. 66-67. A Naturalist's Rambles about Home, 2d. ed., 1894. 



Brehm. Thierleben. Bd. 7. 



Jourdain, S. De 1'intelligence des batraciens. C. R. Ass. franc. 

 Av. Sci., 29me Sess., 1900. 



Knauer, F. K. Beobachtungen an Reptilien und Amphibien in 

 der Gefangenschaft. Wien, 1875. 



Yerkes, R. M. The Instincts, Habits, and Reactions of the Frog. 

 Monogr. Suppl. Psychol. Rev., Vol. 4, 1903. Inhibition and Reinforce- 

 ment of Reactions in the Frog, Kana clamitans. Jour. Comp. Neur. 

 and Psych., Vol. 14, 1904. 



