CHAP, v.] THE PHASES OF LIFE. 689 



heavier and taller than the baby girl, and the maiden of five 

 breathes with her ribs in the same way as does the matron of forty. 

 The woman is lighter and shorter than the man, the limits in the 

 case of the former being from 1*444 to 1*740 metres of height and 

 from 39*8 to 93*8 kilos of weight, in the latter from 1*467 to 

 1*890 of height, and from 49*1 to 98*5 kilos of weight. The muscu- 

 lar system and skeleton are both absolutely and relatively less in 

 woman, and her brain is lighter and smaller than that of man, 

 being about 1272 grammes to 1424. Her metabolism, as measured 

 by the respiratory and urinary excreta, is also not only absolutely 

 but relatively to the body- weight less, and her blood is not only 

 less in quantity but also of lighter specific gravity and contains a 

 smaller proportion of red corpuscles. Her strength is to that of 

 man as about 5 to 9, and the relative length of her step as 1000 to 

 1157. 



From birth onward (and indeed from early intra-uterme life) 

 the increment of growth progressively diminishes. At last a point is 

 reached at which the curve cuts the abscissa line, and the increment 

 becomes a decrement. After the culmination of manhood at forty 

 and of womanhood at the climacteric, the prime of life declines 

 into old age. The metabolic activity of the body, which at first 

 was sufficient not only to cover the daily waste, but to add new 

 material, later on is able only to meet the daily wants, and at last 

 is too imperfect even to sustain in its entirety the existing frame. 

 Neither as regards vigour and functional capacity, nor as regards 

 weight and bulk, do the turning-points of the several tissues and 

 organs coincide either with each other or with that of the body at 

 large. We have already seen that the life of such an organ as the 

 thymus is far shorter than that of its possessor. The eye is in its 

 dioptric prime in childhood, when its media are clearest and its 

 muscular mechanisms most mobile, and then it for the most part 

 serves as a toy ; in later years, when it could be of the greatest 

 service to a still active brain, it has already fallen into a clouded 

 and rigid old age. The skeleton reaches its limit very nearly at 

 the same time as the whole frame reaches its maximum of height, 

 the coalescence of the various epiphyses being pretty well completed 

 by about the twenty-fifth year. Similarly the muscular system in 

 its increase tallies with the weight of the whole body. The brain, 

 in spite of the increasing complexity of structure and function to 

 which it continues to attain even in middle life, early reaches its 

 limit of bulk and weight. At about seven years of age it attains 

 what may be considered as its first limit, for though it may increase 

 somewhat up to twenty, thirty, or even later years, its progress is 

 much more slow after than before seven. The vascular and digestive 

 organs as a whole may continue to increase even to a very late 

 period. From these facts it is obvious that though the phenomena 

 of old age are, at bottom, the result of the individual decline of the 

 several tissues, they owe many of their features to the disarrange- 

 F. 44 



