Probably the failure to realize that the digestive processes of children are different from those of adults, has been the cause of more deaths of infants than any other one form of ignorance. Although long known scientifically, this fact is still unrecognized by a large proportion of mothers.
The differences in instinctive tendencies and in emotional and intellectual activities of children and adults are equally great, though less easily expressed in brief terms. It is with this problem of the difference between children and adults that the science of child study is especially concerned. It is because of the nature of these differences, also, that the impracticability of the application of adult methods to the securing of child welfare is evident.
The problem to be solved is by no means an easy one. The characteristics of human beings are so infinite in number that the noting of differences between children and adults is an endless task. This expresses only a small part of the difficulty, however, for what the individual is, depends largely upon the way in which his many characteristics are combined and developed. Moreover, the changes in characteristics and their combination during development are not uniform as the child grows into the man. Not only are some of the changes greater than others and hence their relative proportions modified, but the changes are much more rapid at one time than at another. Again, one kind of change, as for example, growth in height, is taking place rapidly, while growth in diameter is nearly at a standstill. Later the reverse is true. Mentally, the same relation may be found between imagination and reasoning, or ambition and altruism.
Much has already been done in discovering the prominence of certain characteristics at different stages of development, but the details are yet to be worked out. It will never be possible to say for any individual, however, just when certain characteristics will be prominent. Even the most fundamental characteristics of physical development, such as the rapid growth in height that occurs near the beginning of the teens, come several years earlier in some individuals than in others. If the racial and family characteristics are known a closer approximation may be made. A child of the southern race and of a family maturing early, even for that race, will have his period of rapid growth much earlier than a child of the northern race, but in the same family individual differences will be found according to which line of ancestry is most prominent in the physical characteristics of the child.
In addition to these native differences, racial, family and individual, it is a well-established fact that in man, as in all other organisms, rate and amount of development are determined, not only by inner tendencies, but also by outer influences of climate, food and exercise and by special accidents or diseases. A child whose growth or development has
