486 PEDIATRICS 



opment grow and become stronger, the mortality falls, diminish- 

 ing considerably as early as the second and third years, and reach- 

 ing its lowest point in the period between the sixth and tenth 

 years of life. The occupation of the male, the sexual activity of 

 the female, cause a rise in the mortality from the twentieth year 

 on. In the later age-periods the physiologic sinking and extinc- 

 tion of the life energy finds expression. Haller has expressed this 

 relation in these characteristic words: "Infantes mori possunt, 

 senes vivere non possunt." Infants may die, old people cannot 

 live. 



On Table 2 the mortality rate of a certain group of people based 

 on the official German statistics is expressed, along with the curve 

 of the sinking energy of life. 



This survey brings me to what I may call the second law of 

 growth. The functional development of each individual organ, 

 measured by the absolute degree of ability for work, takes during 

 childhood a rising course, which, however, is different for each 

 organ, and which as a rule shows a much steeper course than that 

 of the growth curve. Unfortunately we lack the scientific data 

 which would enable us to display graphically the gradual growth 

 of the development and the functional ability of the most important 

 organs of the circulatory, respiratory, digestive tract, etc. In 

 general, however, we may conclude on the basis of anatomic and 

 physiologic data that this occurs comparatively quickly, while other 

 functions, like muscular power, reach their maximum at a much 

 later date. We may consider the overcoming of influences injur- 

 ious to the organism, in other words, the degree of the power of 

 resistance, as the common result of all these powers, which finds an 

 expression in the statistics of the frequency of diseases and deaths. 

 That the measure so obtained is only relatively useful, and even then 

 only under certain definite suppositions, is seen by the considera- 

 tion of the first section of intra-uterine life. Although here the organs 

 have the least power of resistance, diseases rarely occur on account 

 of the protected condition of the fetus. But the transition into 

 extra-uterine life already necessitates a wonderful precision of pre- 

 formed mechanisms. The least failure of these causes the greatest 

 danger to the life of the child, and thus is explained the high mor- 

 tality peculiar to the act of birth and the period immediately follow- 

 ing. This is aided by the conditions of extra-uterine life being felt for 

 a time by the new-born as a direct irritant, whose harmful influence 

 can only be lessened by the most constant and proper care. The 

 more backward the development of the child (premature birth), 

 the less favorable the environment (poverty, illegitimacy, unsuit- 

 able nourishment), so much the smaller is the expectation of pre- 

 serving the life of the child. Under unfavorable social conditions, 



