THE CAUSES OF DEATH 131 



die in the first year of life from breakdown of the ali- 

 mentary tract and its associated organs. After the low 

 point, which falls in the relatively early period of 7 to 12 

 years of age, there is a rapid rise for about ten years 

 in the specific rates of mortality, followed by a slowing 

 off in the rate of increase for the next ten or fifteen years, 

 after which point the curve ascends at a practically uni- 

 form rate until the end of the span of life. 



Figure 34 shows the trend of the specific mortality 

 from breakdown of the nervous system and sense organs. 

 This organ group, on the whole, functions very well, giv- 

 ing a relatively low rate of mortality until towards the 

 end of middle life. Then the specific rates get fairly 

 large. The low point in this curve is, as in most of the 

 others, at about the time of puberty. From then on to 

 the end of the life span the specific rates increase at a 

 practically uniform rate. The female curve everywhere 

 lies below the male curve except at the extreme upper 

 end of the life span. Before that time, and particularly 

 between the ages of 20 and 50, the business of living 

 evidently either imposes no such heavy demand on the 

 nervous system of the female as it does on that of the 

 male, or else the nervous system of the female is organi- 

 cally sounder than that of the male. The former sug- 

 gestion seems the more probable. 



That breakdown and failure to function properly, of 

 the skin as an organ system, is a relatively insignificant 

 factor in human mortality, is demonstrated by Figure 35. 

 From a specific death rate of about 1 per thousand in 

 the first year of life it drops abruptly, practically to zero, 

 in early childhood. At about the time of puberty it be- 

 gins to rise again, and ascends at a steady rate during 

 all the remainder of life. The final high point reached 



