484 THE POPULAR SCIENCE MONTHLY 
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 
Jess 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 differ- 
ences, 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 char- 
acteristics 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 indi- 
vidual is, depends largely upon the way in which his many character- 
istics are combined and developed. Moreover, the changes in charac- 
teristics 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, 
:t is a well-established fact that in man, as in all other organisms, rate 
and amount of development are determined, not only by inner tenden- 
cies, but also by outer influences of climate, food and exercise and by 
special accidents or diseases. A child whose growth or development has 
