THE BREEDING BEHAVIOUR OF THE FROG I65 



In R. temporaria it seems that a female is recognized positively by 

 some character that is pecuhar and which she retains after oviposition. 

 The factors that in other species are effective for sex-recogiiition 

 merely determine in this species whether she will be retained or 

 released after she has been recognized as a female and seized. The 

 recognition occurs only on contact. Owing to the angle at wliich the 

 animals float, it is the fingers of one frog that come into contact with 

 the back of another but, below water, it is the nose of the animal that 

 touches first. Now the skin of a breeding female of this species is very 

 noticeably different from that of a male, hi the female there appear on 

 the posterior part of the back, thighs, flanks and the sides of the head a 

 large number of so-called "pearly granulations" that were described and 

 investigated in detail by Huber (1887). He found that, although the 

 structures themselves are horny and impart to the skin a roughness like 

 sandpaper, the bases are provided with a special innervation, and he 

 concluded that they have a tactile function. Whatever may be the 

 sensation that the female derives from them, and whatever part they 

 may play in her life, it seems likely that they have a great importance for 

 the males, for they provide him with a means of recognizing his mate. 

 I found that it was easy to sort males from females by touch alone. 

 The contrast is heightened by the very shppery skin of the males, 

 which is developed also in the breeding season. There is no actual 

 proof that these structures act in the way I suggest, except the observa- 

 tions of the intense action of the males as they brushed past the females. 

 Sight also plays a part. Sometimes, a male frog would catch sight of 

 his own reflection in the mirror and swim croaking towards his image. 

 This confronting of ont male by another is a noticeable feature of the 

 behaviour in the ponds. It is possible that this is one of the ways in 

 which the breeding colony is kept compact, and, perhaps, the function 

 of the male sex-croak is to draw the males together. 



Fighting 



It is now known that, in general, the fighting of animals is mainly 

 bluff". The vanquished animal breaks off" the fight before he receives 

 much damage, and the victor does not pursue his victory. The ferocity 

 of man towards his own species is probably unparalleled. Tinbergen 

 (195 1, p. 177) in discussing this, considers that there is, even in man, 

 the same instinctive inhibition of the fighting drive, and thinks that it 

 is modem long-range arms that have facilitated wholesale slaughter by 



