48 FUNCTIONAL INERTIA 



ment may vary, how occupation, circumstances, 

 mode of life, climate, &c., may all change and yet 

 how regularly the function continues throughout 

 life, we cannot but be struck with its independence 

 of affectability. Of course the uterus possesses 

 affectability ; toxaemias, anaemias, and nervous 

 discharges will interfere with the rhythm ; and 

 according to Darwin * there is some probability that 

 in very early times the function was established 

 by a cosmic process acting through affectability ; 

 but, having been so established, it is carried on 

 the rhythmic status quo is maintained through 

 inheritance by functional inertia in complete dis- 

 regard of environmental conditions. 



Change the environment as you will, take a little 

 English girl to India, and she will begin to men- 

 struate not at 12 or 13, the age at which the natives 

 do, but at 14 to 17 the time appropriate to her own 

 race. This is the kind of phenomenon that is due to 

 functional inertia. The very fact that the function 

 has its own time of life to appear, continue and 

 disappear independently of external and of many 

 internal conditions, is sufficient of itself to reveal 

 the inertial character. 



It is more particularly in connection with the 

 generative organs that we find rhythm playing a 

 conspicuous part : no doubt these organs possess 

 affectability, are accessible to stimuli, but they as 

 certainly possess a property of independence of 

 environment and of spontaneous phasic activity. 



* Darwin, " Descent of Man/' p. 254. (Murray, 1901.) 



