He thus impregnates his wife at the moment of her greatest sexual vigor, and by abstinence he does not influence the sex of the child after conception. Should he desire a boy, let him keep up his connection for two weeks or more after his wife has got over her monthly turn, at the same time carefully practicing the precaution of withdrawal, described in other pages under the head “Modes of Preventing Conception.” At that period the wife will have partially exhausted her amative powers, when he can be almost certain that a boy will be the result of her impregnation. A curious fact relative to the resemblance of children to their parents has been developed by observation. Where a man is absent from his wife during the period of gestation, the child is almost sure to resemble the mother. On the other hand, an amorous father, who keeps a constant connection with his wife during pregnancy, will cause the child to resemble him. If a woman should become pregnant by one man, and then cohabit constantly with another during her pregnancy, the child would bear a resemblance to the second man rather than to its father. This would surely be the case if she were fond of the latter’s caresses. It often happens that a married couple will have “a run” of children of one sex, and then turn round and breed those of the opposite sex. This may be accounted for by the failing health, and consequent vigor, of the predominating parent. Thus if a woman begins to breed boys, and after having had several, turns round and breeds a number of girls, it is a pretty sure sign that the sexual vigor of her husband is on the wane, or that his bodily health is failing. Should girls come first in rotation, and boys afterwards, the mother’s generative vigor may be suspected of falling off. These are, however, mere suggestive ideas; though readers may understand from them the principle upon which Nature forms the two sexes. I have no doubt that a careful and practical study of the subject may sometimes enable parents to elect the sex of their offspring, on the principle we have explained; but there are so many curious phases in the phenomena of procreation, that any certainty on the subject is out of the question. DEVELOPMENT OF THE FŒTUS.