242 O. ISHII. 



the guinea pigs. And the heat is therefore not so vigorous as it 

 would be under other climatic conditions. The length of the 

 dioestrous period on the other hand seemed to be the same during 

 the warm and cold season of the year. 



Does Contact with the Male Influence the Time of Appearance of 



the First Heat? 



If young female guinea pigs are kept in a cage with males and 

 other guinea pigs of the same descent are kept separated from 

 males, the first heat appears in both lots at the same age. This 

 shows that psychical factors such as the stimulation of the male 

 does not influence those conditions which lead to the first heat. 



The Copulation-reflex of the Heat Period and the Diagnosis of the 



Heat Energy. 



This reflex can be elicited by the male guinea pig seeking 

 copulation, when it touches or gently massages with his forefeet 

 the lumbar portion of the spinal column of the female which is 

 in heat. The female will then lift up the tail and the vagina 

 will be opened in preparation of the copulation. The same 

 reflex can be called forth if an observer touches with his finger the 

 same part of the body of the female guinea pig. The readiness 

 and vigor with which the reflex occurs can serve as a measure of 

 the energy or vigor of the heat. 



Menstruation during Pregnancy. 



I very carefully watched twenty guinea pigs during their state 

 of pregnancy for a sign of menstruation and found in ten no 

 evidence of menstrual secretion, but in the remaining ten there 

 was some secretion present; not all of those however showed 

 signs of heat. The menstrual period is not definite during 

 pregnancy. Statistically my results were as follows: 



Menstruation was noticed in 3 guinea pigs 27 days after copulation 



" 3 " " 30 " 



" 2 " " 40 " 



2 " " had menstrual secretion twice, the first 

 time 15 days and the second time 30 days after copulation. 



While in these cases the swelling of the external genitalia and the 

 secretions are manifest, they are slight. The secreted material 



