OLD AGE. 333 



or a new handicraft appear as very serious undertakings, 

 and as a rule are only indifferently acquired. Yet there 

 can be no doubt that when a capability is lost, then 

 somewhere in the central system a physiological change, 

 if not a structural one, has rendered the cells less active. 

 As behind each functional advance there must be a 

 further structural organisation, so diminished organisa- 

 tion must accompany each loss of power. Of such slow 

 changes in ourselves we are happily for some time 

 unconscious, and the beginnings are to be discovered 

 only by the application of some exact measure of the 

 reaction. In his essay on Old Age, Sir J. Crichton 

 Browne gives some interesting observations bearing on 

 this loss of capability. 1 From these it appears that in 

 England the expertness of the Birmingham button- 

 makers, the Staffordshire potters, and the Bradford 

 weavers increases from the time of entering their trade 

 at about seventeen years up to thirty years of age. 

 From this until forty-five years there is a period of 

 equilibrium, and then a decline sets in. The following 

 table illustrates the manner in which the productiveness 

 of a maker of vegetable ivory buttons, working the same 

 number of hours, decreases with advancing years. 



TABLE 62. SHOWING AT DIFFERENT AGES THE NUMBER OF 

 GROSS PER DIEM PRODUCED BY A SAWYER OF VEGETABLE 

 IVORY BUTTONS. (Szr /. C. Browne.} 



NUMBER OF GROSS PER DIEM. 



40 years 

 45 



55 



100 

 80 

 60 

 40 



Sir J. C. Browne, Brit. Med. Journ., London, 1891. 



