844 THE AMERICAN JOURNAL OF SOCIOLOGY
in general, this is important to know. In like manner it would be interesting to know what characteristics, if any, are in common between the feeble-minded in our institutions and dull children in our schools. These and similar inquiries, when made with care and discretion, might enable us to foresee with some probability the special dangers that this and that child may be subject to, and thus to protect many children from temptations and condi- tions that otherwise might ruin them.
IMPORTANCE OF LARGE NUMBERS.
Where the number of persons studied is large, many sub- divisions can be made, and in this way some of the most impor- tant, yet sometimes unexpected, results are reached. It would be well to know the difference, not only between children of the professional, mercantile, and laboring classes, but between those with American parents and foreign parents. Then, if the num- bers were large enough to admit further subdivisions, we might find the difference between children whose father is American but mother foreign-born, and those whose mother is American and father foreign-born. In all such questions, if there is no striking difference, it is important to know it. Thus the influ- ence of marriage between different races or nationalities upon the offspring might be determined more definitely.
If it should be found, for instance, from the comparison of large numbers, where all possibility of accident or coincidence is eliminated, that the difference between certain classes of chil- dren, such as the criminal, from children in general is quite marked, the question would arise whether such difference is due mainly to heredity or to unfavorable surroundings. In cases where the crime or defect is due to heredity, the treatment would be quite different from those in which environment is the cause.
QUESTION AS TO UTILITY.
But, it may be asked, what as to the utility of studying such questions ? We think it is not only useful, but there is great need of such investigation. We should like to inquire, for instance, as to the utility of studying rocks and plants, arranging them,
