With regard to the laws which regulate the sex of progeny very little is known. Many and extensive observations have been made, but without arriving at any definite conclusions. Nature seems to have provided that the number of either sex produced, shall be nearly equal, but by what means this result is attained, has not been discovered. Some physiologists think the sex decided by the influence of the sire, others think it due to the mother. Sir Everard Home believed the _ovum_ or germ, previous to impregnation to be of no sex, but so formed as to be equally fitted to become either male or female, and that it is the process of impregnation which marks the sex and forms the generative organs; that before the fourth month the sex cannot be said to be confirmed, and that it will prove male or female as the tendency to the paternal or maternal type may preponderate. Mr. T.A. Knight[19] was of opinion that the sex of progeny depended upon the influence of the female parent. He says, "The female parent's influence upon the sex of offspring in cows, and I have reason to believe in the females of our other domestic animals, is so strong, that it may, I think, be pronounced nearly positive," He also says, "I have repeatedly proved that by dividing a herd of thirty cows into three equal parts, I could calculate with confidence upon a large majority of females from one part, of males from another, and upon nearly an equal number of males and females from the remainder. I have frequently endeavored to change the habits by changing the male without success." He relates a case as follows:--"Two cows brought all female offspring, one fourteen in fifteen years, and the other fifteen in sixteen years, though I annually changed the bull. Both however produced one male each, and that in the same year; and I confidently expected, when the one produced a male that the other would, as she did." M. Giron, after long continued observation and experiment, stated with much confidence, that the general law upon this point was, that the sex of progeny would depend on the greater or less relative vigor of the individuals coupled. In many experiments purposely made, he obtained from ewes more males than females by coupling very strong rams with ewes either too young, or too aged, or badly fed, and more females than males by a reverse choice in the ewes and rams he put together. Mon. Martegoute, formerly Professor of Rural Economy, in a late communication to the "Journal D'Agriculture Pratique," says that as the result of daily observations at a sheepfold of great importance, that of the Dishley Mauchamp Merinos of M. Viallet at Blanc, he has, if not deceived, obtained some new hints. He states that Giron's law developed itself regularly at the sheepfold in all cases where difference of vigor was observed in the ewes or rams which were coupled; but he adds another fact, which he had observed every year since 1853, when his observations began. This fact consists--