Not a few students of the problem, however, advocate a rigid segregation as the only reasonable preventive measure, no matter what the expense. They point out that the cost is mounting up higher each year and that we are only increasing it ultimately by procrastination. They urge, moreover, that when counting the cost of the segregation of the feeble-minded we should bear in mind also that we are reducing the expenses of our other charity and penal institutions, since much of degeneracy, pauperism and petty criminality centers in mental enfeeblement. Some believe that colonies can be established which are in considerable measure self-supporting. Doctor Johnstone, for instance, although his estimates of the number of feeble-minded and epileptic is one of the highest, sketches out in a recent paper (in _Pediatrics_, August, 1912) a plan which he considers feasible. But what assurance have we that we can prevent the production of defectives by segregation? In reply may be cited a recent experiment on an extensive scale. Cretinism is a condition due to disease of the thyroid glands. It is characterized by goiter, marked deformities and imbecility. It is hereditary and has been very prevalent in certain valleys of southern Switzerland and northern Italy. Cretin mated with cretin and consequently a large new supply was constantly produced. In recent years in certain communities the sexes have been segregated (see _Eugenic Review_, 1910, Jordan) with the result that in such places cretinism has about disappeared. Coming now to the fourth solution proposed, namely, sterilization,[21] let us consider some of its alleged advantages and disadvantages. =Sterilization.--=First of all, since there is some considerable popular misunderstanding on the subject, it should be made plain that by sterilization is not necessarily, nor in fact generally, meant asexualization, or the removal of the reproductive glands. On the contrary, in the male, sterilization is ordinarily accomplished by an operation known as _vasectomy_, in which a small piece of each sperm duct is removed. Such reports on it as I have found indicate that it is a comparatively simple minor operation which involves no special inconvenience or hardship on the subject beyond the deprivation of offspring. In fact, according to Doctor Sharp's report, in the majority of cases where it has been put into practise the patient has usually submitted voluntarily after having the details of the situation explained to him and has often advised fellow delinquents to do likewise.