THE (ESTROUS CYCLE IN THE MAMMALIA 67 



known to occur. ^ The voice also is Kable to be affected at the 

 menstrual periods, and the skin and breath sometimes have a 

 pecuhar odour. Mental depression may exist, and be accom- 

 panied by nervous pathological phenomena. 



According to the upholders of the " WeUenbewegung " 

 hypothesis ^ the reproductive life of the human female consists 

 of a succession of wave-hke periods which follow the monthly 

 cycle. Thus, according to Stevenson,* the curve of temperature 



E G 



d 14 IS 16 17 la 18 ' 



Fig l.^Diagram illustrating the "WeUenbewegung" hypothesis. The 

 curve AB represents the varying intensity of the vital processes during 

 the twenty-eight days of the menstrual cycle. The numbers between 

 m and m represent the days occupied by menstruation. (From Sellheim.) 



is above the mean Une for about half the month, when it rises 

 to half a degree above the mean. It falls below the mean Une 

 just before the onset of menstruation, during which it remains 

 about half a degree below. Similar results were obtained by 



' See p. 350, Chapter IX. 



^ Godman, "The Cyclical Theory of Menstruation," Amer. Jour. Ohstet., 

 vol. xi , 1878. Reinl, " Die WeUenbewegung des Lebensprozesses des Weibes," 

 Volkmann's Sammlungklin. Vortrdge,'!^ 0.273. Ott, " Les lois de la periodicity 

 de la fonction physiologique dans I'organisme feminine," Nomielles Arch, 

 d'Obstet. a de Gynic., 1890. 



' Stevenson, "On the Menstrual Wave," Amer. Jour. Obstet., vol. xv., 1882. 



