CHAP. m.J THE PHASES OF LIFE. 405 



This fall, however, is temporary only ; the curve soon rises again 

 and with some irregularities attains a maximum between the 

 twelfth and fifteenth year, from which point onwards it falls 

 rapidly with some minor irregularities. These marked variations 

 in the increment of growth which are obviously connected with 

 and preparatory to the important change which we call puberty, 

 are seen in the curves both of stature and of weight, the changes 

 in weight occurring however rather later than those of stature, 

 and both being somewhat different in boys from what they are in 

 girls. Both are also influenced by the conditions of life ; but a 

 study of the curves of growth of young people living under various 

 surroundings, while it teaches the great importance of properly 

 administering to the wants of youth, at the same time illustrates 

 the recuperative elasticity of the bodily frame , it may often be 

 observed that the ill effects of adverse circumstances, provided 

 they be not too great, are soon recovered from under the influence 

 of a happy change ; food and comfort will turn the abnormal fall 

 in the curve of growth of a starved waif into a sharp rise. 



Lastly, we may study growth by observing the actual rate of 

 growth, by measuring the magnitude of the fraction of the total 

 weight which is added to the weight in a given time ; we take 

 weight because this is the most significant element of growth. 

 When this method is adopted, an examination of such statistics as 

 are available with regard to man, confirmed by the results of 

 careful observations on young animals, tends to shew that the rate 

 diminishes continually from birth onwards, the diminution being 

 rapid at first but slower afterwards, and being broken by various 

 irregularities. In other words, the power of growth diminishes 

 continually though somewhat irregularly throughout life, and a 

 like diminution apparently obtains in intra-uterine existence. It 

 seems as if the impetus of growth given at impregnation gradually 

 dies out. 



974. The saliva of the babe, very scanty at first and not 

 abundant until teething begins, is active on starch though less so 

 than in the adult, and its gastric juice, unlike that of many new- 

 born animals, has good peptic powers, and its pancreas good tryptic 

 powers, though apparently the pancreatic action on starch is feeble. 

 From this we may infer that its digestive processes are in general 

 identical with that of the adult though ill suited for any large 

 amount of starch in the food; and they are feeble, since the 

 faeces of the infant contain a considerable quantity of undigested 

 food (fat, casein <fec.), as well as unaltered bile-pigment, and unde- 

 composed bile-salts. 



The heart of the babe, as shewn in the preceding Table, is, 

 relatively to its body-weight, larger than the adult, and the 

 frequency of the heart-beat much greater, viz about 130 or 140 

 per minute, falling to about 110 in the second year, and about 90 

 in the tenth year. Corresponding to the smaller bulk of the body, 



