The rapidity with which the first cells grow to form tissues, once they have been stimulated by union is very great, and from the ovum, which on the day of fertilization is only 1/120th of an inch in size, the growth is so rapid that it is ten times as big at the end of fourteen days. By that time the length is one-twelfth of an inch, and it weighs one grain. By the thirtieth day the tiny embryo is already one-third of an inch big, and were it practicable, which, of course, it is not, to remove it living from its bed of tissue in the mother’s womb and examine it, even with the naked eye, and still more with a magnifying glass, it would be possible to see the rudiments of the legs, head and arms which are to be. By the fortieth day the embryo is about one inch in length, and the shape of the child, which it is to be, is quite clearly visible. Dark points are to be seen where later it will have eyes, nose and mouth, and there is already a hint of its backbone. Meanwhile, as may be realized, although to have grown in forty days to the size of an inch from a minute speck 1/120th part of an inch is a great and rapid achievement, nevertheless the existence of a thing one inch big within her makes little outer difference to the mother, and all the earlier weeks and months of the growth of this tiny organism do not yet take more visible effect on the mother’s body than to enhance its contour. After the first child this effect is less noticeable, and a woman may be unaware that she is about to become a mother. The first sign in a really healthy woman generally is in the form of her breasts, which sometimes begin to enlarge by the second or third week. It is said that the more healthy and perfectly fitted for motherhood a woman is, the sooner her breasts show signs of the effect of the developing embryo but, particularly with a woman who has already borne a child, there may be no external sign until at least three months have passed. By the sixth week, the limbs and most essential parts of the child are apparent, and there are the minute indications of the beginning of its future sex organs. It is evident, therefore, that if there is any desire to control the sex of the coming child, it is already too late by the sixth week to do anything, were it ever possible reliably to control sex at any time. It is, therefore, apparent that any passionate desire for a child of one or the other sex which the mother may indulge in when she knows she is about to be a mother, say by the third or fourth month, is futile. It may also be injurious (see Chapter XIV). By the second month, nearly all the parts are fully apparent, even the eyelids are visible in the embryo and a tiny nose begins to project; fingers and toes can be seen, and some centres of bone begin to harden, as for instance, in the ribs.