Males. Females. Differences. Grammes. Grammes. Total weight 1908.18 1708.11 200.07 in favor of males Kidneys 16.87 17.19 2.67 in favor of males Superrenal glands 5.15 6.43 0.32 in favor of females Liver 88.35 96.31 1.28 in favor of females Spleen 2.59 2.38 7.90 in favor of females Thymus 3.89 3.97 0.21 in favor of males Heart 10.97 12.60 0.08 in favor of females Lungs 47.29 44.62 1.63 in favor of females Brain 236.94 235.17 1.17 in favor of males "These figures thus show us," says M. Loisel, "a preponderance already existing in favor of the females as regards the kidneys, the superrenal glands, the liver, the thymus and the heart; this predominance is the more noticeable since the total weight of the body is larger in the male than in the female." If now we take the relation between the total weight and the weight of the organs which are heaviest in the male, we find that the proportion is still in favor of the female: PROPORTION OF TOTAL WEIGHT. Males. Females. Spleen 1 to 736 1 to 718 Lungs 1 to 40 1 to 38 Brain 1 to 8 1 to 7 The organs here examined, brain included, are thus absolutely or relatively heavier in the female foetus than in the male foetus. M. Loisel has also examined into the proportion of the weights of the different organs to the total weight according to the age of the foetus. He has prepared a table, from which I take only the figures concerning the brain: Proportion of AGE TOTAL WEIGHT weight of brain to total weight. Males Females Males Females Grammes Grammes 3 Months 58.33 65.96 1/6.5 1/7 4 Months 167.25 182.58 1/7.3 1/6.6 5 Months 336.33 295.00 1/7.6 1/7.5 6 Months 732.58 636.00 1/8.3 1/7.3 The weight of the male foetus, which is below that of the female foetus, at three months, when the sex has just been determined, grows more rapidly and the proportion between the weight is always to the advantage of the females from the fourth month on. "To sum up," says M. Loisel, "all the organs are heavier in the female foetus than in the male foetus up to about the fourth month. The predominance then passes over to the male, but only for the lungs and the organs for sex-union, thus the cardiac muscle always remains heavier in the female. The organs which are of real service to the individual during the embryonic life always remain more developed in the female sex.