Every mother, if not her children, has often heard the word “heredity” mentioned. The offspring is part and parcel of the parents, and inherits, somewhat changed or modified perhaps, not only their good qualities, their strength of body, brain, and constitution, but their diseases also, if they have any. There is no mystery about that, as some medical men tell us. It would be a mystery if it were the reverse. If you take a cutting off a pure red rose, you could scarcely expect it when grown into a bush to develop yellow roses. It is part and parcel of the parent, and so is the child. But separate life and the mode or manner of living may alter even inherited complaints, or prevent their showing forth at all. It does not follow as a constant rule that the children of, say, scrofulous parents shall be consumptive, or that those of parents addicted to drink and dishonesty shall follow the parental lead. It is this fact that gives one such hope in treating the ailments and guiding the young lives of those who may be supposed to be born with a taint of impure blood. Note, mother, please, that I have said “_young_ lives” in my last sentence, because it is when young, and only then, that much good can be done to combat the evils of heredity. We are sometimes told that the particular ailment handed down may skip one generation and appear in the next. This should only give us additional certainty that the trouble may be eradicated entirely. For Nature does not skip generations in the manner some scientists would have us believe. If an ailment, say phthisis or consumption, is the trouble in one family and the children thereof escape, while the grandchildren are attacked, one of two things may have happened; the first generation of the afflicted ones had been reared in circumstances inimical to the dispersing of the disorder, it lay latent in their blood and revivified under circumstances favourable to it, in the grandchildren, or—this is just as likely—the seed of the disease died in the first generation, and the second were infected by ordinary means. Phthisis is infectious: this should always be born in mind, and a consumptive person should invariably sleep alone in the airiest and best ventilated room in the house.