13. CAUTION.--Any attempt, on the part of the mother, to destroy her child before birth, is liable, if unsuccessful, to produce murderous tendencies. Even harboring murderous thoughts, whether toward her own child or not, might be followed by similar results. "The great King of kings Hath in the table of His law commanded That thou shalt do no murder. Wilt thou, then, Spurn at His edict, and fulfill a man's? Take heed, for He holds vengeance in His hand To hurl upon their heads that break his law."--RICHARD III., _Act 1._ * * * * * {295} How to Calculate the Time of Expected Labor. [Illustration: The Embryo In Sixty Days.] 1. The table on the opposite page has been very accurately compiled, and will be very helpful to those who desire the exact time. 2. The duration of pregnancy is from 278 to 280 days, or nearly forty weeks. The count should be made from the beginning of the last menstruation, and add eight days on account of the possibility of it occurring within that period The heavier the child the longer is the duration; the younger the woman the longer time it often requires. The duration is longer in married than in unmarried women; the duration is liable to be longer if the child is a female. 3. MOVEMENT.--The first movement is generally felt on the 135th day after impregnation. 4. GROWTH OF THE EMBRYO.--About the twentieth day the embryo resembles the appearance of an ant or lettuce seed; the 30th day the embryo is as large as a common horse fly; the 40th day the form resembles that of a person; in sixty days the limbs begin to form, and in four months the embryo takes the name of foetus. 5. Children born after seven or eight months can survive and develop to maturity. * * * * * {296} DURATION OF PREGNANCY. DIRECTIONS.--Find in the upper horizontal line the date on which the last menstruation ceased; the figure beneath gives the date of expected confinement (280 days).