24O O. ISHII. 



1 8 days) than the average, the animals were either in a weak or 

 pathological condition, and that menstrual irregularities sub- 

 sequently followed. My continuous experiments made on this 

 subject covered both winter and summer of 1913, and the winter 

 of 1914 in Granby, Mass., and during all these seasons, through 

 all temperatures, the same condition prevailed. 



GENERAL PHENOMENA OF MENSTRUATION AND HEAT AND 



PREGNANCY. 



Physical Phenomena of Menstrual Period. 



One of the foremost indications of the approach of the period 

 of menstruation or heat is the physical change noticed in the 

 animal. The muscles and joints become tender and relaxed, 

 and by this change it can be determined, whether the animal is 

 normal and healthy. During this period nervousness and a 

 certain mental depression are noticeable; and when the period is 

 over the symptoms most apparent indicate fatigue or exhaustion. 

 However, by the end of the second or third day this fatigue has 

 entirely disappeared and within I ^ to 2 days after cessation of 

 heat a normal animal has regained its full vitality. 



Relation between Menstruation and Falling Out of Hair. 



I have found, particularly in the guinea pig, rat and rabbit an 

 additional visible sign of heat, viz., the falling out of the hair in 

 unusual quantities during the period of menstruation; as a 

 result of this happening, the external appearance of the animal 

 becomes somewhat glossy. We can determine this by comparing 

 the ease with which the hair can be made to fall off by rubbing the 

 skin in the menstruating animal, on the one hand, and in the 

 infantile, pregnant, amcestrous female or male, on the other hand. 

 In exceptional cases a slight menstrual secretion may develop 

 during pregnancy; in this case the falling out of the hair is slight 

 in accordance with the slight degree of menstrual activity. 



Specific Odor of Females during the Period of Heat. 



Many (but not all) males can evidently clearly distinguish 

 between females which are in the period of heat on the one hand 

 and those in which there is merely menstrual secretion and in 



