The Eugenist does not propose to extend the operation of sterilisation beyond the classes above mentioned. It does not, however, regard these as exhausting the categories of undesirable procreators. Already there are numerous suffering and semi-cured adults whose children would inherit the diseases, weaknesses, and evil tendencies of their ancestors. Tuberculosis, syphilis and St. Vitus's Dance sufferers are specimens of this class. As Eugenics advances we may learn more of the racial poisons, and a scientific black-list may be drawn up of those hereditary taints which inflict most harm on the community. Doctors should have to notify the authorities of these diseases and the patient should be encouraged to frankness and helped to a cure. In all such cases kind but firm warning must be given against procreation. The failure to heed such warning should inevitably result in imprisonment--a very short term will suffice, for with Eugenics established as a rule of society, the State could afford to be patient. The elimination of the unfit would make rapid strides, and the offspring of tainted parents evading the law in one generation would be less and less likely to escape in the next generation. It may be that the State will be contented with the negative side of Eugenics. It may be that it is the more important because we are daily increasing the elements which if not checked will destroy our civilisation. Negative Eugenics is as imperative a necessity as the protection of our coasts from invasion or the destruction of potato blight. Positive Eugenics represents the attempt to encourage breeding from every healthy stock. Its methods will vary with the views of society from time to time. Its machinery will be by State-interference or by private experimental enterprise according as socialist or individualist ideals are current. I do not wish to commit Eugenists who are by no means agreed on this point, but my personal view is that individual experiments cannot possibly go far beyond public opinion, whereas, "the State can do no wrong" if it endows, undertakes and is responsible for experiments limited in extent but far reaching in principle, so long as such experiments are based on scientific probabilities and are supported by enlightened competent judges and do not outrage the humane sentiment of the race. Drastic individual experiments, involving however few people, will always be subject to interference at critical moments by mobs, governments, vigilance societies, etc. It is not wise to ignore this factor; it is not necessary even to deprecate it; nay, it has its advantages. The omnipotence of the State rests not merely in its power of arms; a State experiment, even though not initiated by the people, can be stopped by the people. The electors' power ultimately to interfere makes for tolerance.