292 PHYSIOLOGY CHAP. 



activity, climate, social conditions, may hasten or retard the 

 beginning of the menopause, just as they influence the advent of 

 puberty, that is the appearance of the first menstruation. It is 

 generally supposed that very early menstruation causes the 

 change of life to take place earlier, "prius pubescentes, prius 

 senescunt" (Virey); on the other hand, observation proves that 

 numerous conceptions make it take place later. 



Taking the statistics drawn up 'by Mayer, Tilt, Guy, and 

 Peuch, we find that the change of life takes place : 



At from 35 to 40 years of age in 12 per cent of women, 

 41 to 45 26 



46 to 50 41 



51 to Do ,, ,, 15 



and in 6 per cent either before or after these limits. 



We may on the whole adopt Kisch's view that the menstrual 

 function begins later and lasts longer in northern countries ; that 

 scanty menstruation and moderate sexual activity tend to retard 

 the change of life, whereas too early sexual relations, childbirth 

 at too short intervals, and unhealthy confinements bring it about 

 sooner ; also that favourable conditions as to nourishment and 

 social environment prolong the menstrual period. 



Some writers, Halford, Church, Mendel, De Fleury amongst 

 others, are of the opinion that in men too a number of dis- 

 turbances take place at about fifty years of age which they 

 regard as equivalent to those of the change of life. They have 

 noticed in individuals who showed no signs of mental weakness 

 or arteriosclerosis, and up to this age were well -nourished and 

 enjoyed excellent health, a sudden and rapid deterioration of the 

 whole organism, usually only of a temporary nature. This seems 

 to be a critical period, which, beginning with gastric and cardio- 

 vascular disturbances, affects all the other functions. The 

 patient's character changes, he suffers from depression and fears, 

 complains of anxiety and restlessness, feels weak, and notices a 

 failure of memory and decreased sexual desire. Other symptoms 

 are : sudden congestion of the head, a feeling of oppression with 

 sudden breaking into perspiration, palpitation of the heart, 

 insomnia, giddiness, headaches, multiple paraesthesia. This 

 supposed critical period covers a period of from ten months to 

 four years, and is attributed by Mendel to a diminution of the 

 secretions (internal or external ?) of the glands of the generative 

 system. The theory is very suggestive, but does not seem to me 

 to rest on a sufficiently large number of scientific observations 

 which cannot be explained as casual morbid symptoms, arising 

 from quite other causes than those suggested by Mendel. 



VI. After the period of youth and maturity comes that of 

 the decadence of the organism. Growing old is caused by the 

 nature of the exchange of material and energy in the living 



