AIMS OF MODERN PEDIATRICS 487 



the mortality rises to 70 % of the births, while in well-to-do fami- 

 lies it may sink to 10%, or even lower. Much more important than 

 these external influences is the rapid development of the organs 

 occurring at this time, especially that of the digestive tract, which, 

 according to Bloch's investigations, reaches its full histologic de- 

 velopment from the third to the fourth year of life. This rapid 

 improvement in resisting power, associated with high vital energy, 

 together with the care and protection which guards the child in 

 the parents' house, brings about the period of greatest health, 

 which continues to the end of childhood, and in which disease and 

 death sink to a minimum. The functional development, however, 

 is by no means completed yet with this stage. Rather now begins, 

 after the preservation and protection of life under normal condi- 

 tions has been assured, the growth of that power and reserve strength 

 which enables the adult to take up the struggle for existence and 

 to care for the continuance of the species under the best possible 

 conditions; the development of strength and activity in the mus- 

 culature, becoming accustomed to fatigue, to different kinds of 

 nourishment, to climatic influences, and especially the develop- 

 ment and training of the mental powers. Into this period falls also 

 the strengthening of the protective influences necessary for the 

 overcoming of infectious diseases, the acquiring of immune sub- 

 stances, etc. 



The occurrence of this long so-called puerile period, which is given 

 over mostly to the functional development by relatively slight 

 increase in length and weight, belongs, like the long duration of 

 childhood, among the most eminent peculiarities of development 

 in the human species. There is no doubt that man owes to this 

 slow development and maturing not only the high state of his 

 mental and physical abilities, but also his enormous power of accom- 

 modation and functional adaptation which enables him, in con- 

 trast to lower forms of life, to exist under the widest extremes of 

 climate, foods, and habits of life, and thereby to make himself 

 really the lord of the world. It would, however, be a fundamental 

 error to believe that this progressive development of functions 

 and organs, which characterizes childhood, occurs to an equal ex- 

 tent in all parts, like the growth of a crystal, which increases in 

 size by addition of equal amounts over the whole surface of the 

 nucleus. The study of embryology, which shows such remarkable 

 changes in the form of the embryo, protects us from this unfor- 

 tunately widespread opinion which regards the child as the exact 

 image in small size of the adult. The table devised by Langer shows 

 the great differences which on closer observation are seen to exist 

 between the form of the child and that of the adult. But that not 

 only the outward form, but also the internal organs experience 



