AIMS OF MODERN PEDIATRICS 489 



change from intra- to extra-uterine life and the atrophy of fetal 

 organs; hyperemia and desquamation of the external coverings. 



(2) Nursing period (first year of life). Characterized by the neces- 

 sity for exclusive milk diet on account of the functional weakness 

 of the digestive tract, also a great consumption of nourishment 

 and considerable increase in bodily size (trebling of birth weight) 

 marked growth of the brain ; all other functions remain back- 

 ward. 



(3) Milk-teeth period (second to fifth years of life). Character- 

 ized by rapid growth and formation of the skeleton, eruption of 

 milk-teeth, learning to walk and to talk. 



II. Childhood : Pueritia. (Sixth year to puberty.) Character- 

 ized by special development and exercise of the musculature, by 

 increase of all functional activities, and by slowly progressing 

 growth of the body. Passage of the child from the family life into 

 social life (school). Beginning differentiation of the sexes. 



III. Age of puberty (in boys from the sixteenth year, in girls 

 of the Germanic race, from the thirteenth year on). In the latter, 

 beginning menstruation. Awakening of sexual impulses and de- 

 velopment of secondary sexual characteristics. 



I have limited myself to giving the physiologic characteristics 

 of these periods very briefly. On the contrary, I will try to picture 

 more extensively their close and important relations to pathology. 

 If we conceive of disease as the physiologic reaction and defense 

 of the organism against the disease-producing agency, it is apparent 

 that the physiologic condition present at the time determines the 

 kind and course of the process. As this is true for childhood in 

 general as compared with maturity, so it is also for the different 

 periods of growth, which, depending on the degree of development, 

 show such great physiologic differences. In the first period of life, 

 especially, these are so great that under the influence of local con- 

 ditions there has developed a further specialization within the 

 limits of pediatrics of such physicians, hospitals, and clinics as are 

 especially concerned with the care and diseases of the nursing period. 

 Even if I do not consider this tendency to separate as justified, 

 still it will serve to demonstrate the great compass and variation 

 of the study of children's diseases. 



The relation of the periods of growth to pathology are based, as 

 already stated above, on the fact that the special physiologic pecu- 

 liarities of each period bring with them a similarity in the course 

 of life, and therefore opportunities for certain diseases such as do 

 not occur at any other time. The undeveloped condition of the 

 organs in general helps along by causing a lessened power oT re- 

 sistance against all disturbances, and further, the organs while 

 growing rapidly are disposed to diseases to an especially high de- 



