436 



REPRODUCTION AND DEVELOPMENT 



whole body. Another possible source of relief lies in the fact that the 

 body temperature is highest a short time before menstruation. Sexual 

 desire is increased over the average just before and also after the menses, 

 the period itself being the time of heat or rut in the brutes. In the human 

 male also there appears to be a somewhat similar periodicity of desire 

 dependent doubtless on the accumulation or else on the liberation from 

 the testicular tubules of spermatozoa. It is not apparent that the moon 

 has anything to do with the periodicity in either sex the notion is one 

 of the many from the superstitious past. The social, medical, and legal 

 relations of menstruation make it and its accompaniments (such for 

 example as nervous instability), matters of no small practical importance. 



FIG. 249 



100 



75 



50 



25 



5 6 



8 I 9, 10 11 12 13 



20 21 22 23 24 25 



27 28 







14 15 16 17 18 19 



Graphic suggestion of the fluctuations of the vital processes as related to menstruation. The 

 days of the lunar month are indicated on the abscissa-line C D; menstruation lasting part of 

 the six shaded days, m, n. The percentages of intensity of the life-processes (including pulse- 

 rate, blood-pressure, heat-radiation, muscular strength, lung-capacity, strength of respiration, 

 reaction-time of patella reflex) are indicated numerically along the ordinate-line C E, by the 

 varying height of the curve A B, in the ordinary way of the graphic method. Thus, just 

 before menstruation vitality is at its height, ready to be reproduced. (Nagel.) 



The uterine phenomena causing the monthly flow are relatively simple. 

 The columnar ciliated epithelium of the uterine body, together with the 

 outer portions of the mucosa beneath it, degenerate more or less and are 

 washed out of the uterus and vagina by the flow of blood from the capil- 

 laries and smallest arterioles lacerated in this process. In some women 

 this epithelial degeneration may be almost or quite lacking. Both the 

 uterine glands and the tissue between them undergo fatty degeneration 

 and are excreted, the layer of tissue given off being from 3 to 6 mm. thick, 

 and appearing sometimes as a complete cast of the uterine interior walL 

 The blood passed into the vagina because of its large admixture with 



