102 CALVIN P. STONE 



female, thus placed does a variable amount of cage exploration. 

 While doing this, she is followed by the male with his activities 

 directed almost wholly to her. If he is too vigorous in vaginal 

 sniffing, nibbles too deeply in search for parasites, or impedes 

 her progress by playful assaults, she sometimes resists with a 

 back-kick of the hind foot, or by moving into a corner of the 

 cage where she is less accessible to his assaults. The receptive 

 female usually makes a less extensive round of exploration. When 

 approached by the male in the manner described above, she 

 assumes a tense attitude that involves the general musculature 

 of the body and limbs* Frequently this tension is accompanied 

 by slight vibratory movements of the head and shoulders suffi- 

 ciently general in its distribution to give to the whole body a 

 shivering effect. The shiver may last from one to two seconds. 

 After a moment of smelling or licking, on the part of the male, 

 the receptive female runs forward in the cage a short distance or 

 bruskly shifts her position so that the root of her tail is directly 

 in front of the male. This running movement resembles the 

 quick irregular gallop of the guinea-pig. If the male is sexually 

 aroused by this movement and pursues her across the cage, as 

 is usually the case after she has moved one or more times, she 

 runs only a short distance and halts upon being overtaken by the 

 male and caught in the copulatory clasp. She halts instantan- 

 eously when firmly clasped. 



Although the responses just described are typical, there are 

 many variations from this type. Some females, persistently, 

 and nearly all observed at the onset of the oestral period, re-act 

 to the vaginal smelling and licking by running wildly about 

 the cage, kicking with the hind foot, and, not infrequently, biting 

 at the pursuer. 



In many cases the male begins to copulate within the first 

 minute after the female is placed in the cage. In some instances, 

 however, a variable number of pre-copulatory activities of short 

 duration precedes the act. These activities, for the most part 

 irrelevant in nature, occur in promiscuous order. (They never 

 suggest a type of courting behavior.) The acts appearing most 

 frequently are: nibbling at the head or body of the female, 



