THE CESTROUS CYCLE IN THE MAMMA IJA 67 



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

 menstrual periods, and the skin and breath sometimes have a 

 peculiar 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-like periods which follow the monthly 

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



FlQ 1. — Diagram illustrating the " WellenbeweguDg '' hypothesis. The 

 curve AB represents the varying intensity of the vital processes during 

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

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



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

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

 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," ^m«r. Jour. Obstet., 

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

 Volhmaim's Sammlung hlin. Vortrage, No. 273. Ott, " Les lois de la periodicite 

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

 d'Obstet. et de Gynic., 1890. 



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



