doms. He is led to believe that the sex depends upon the comparative vigour of the parents. To obtain an excess of female offspring the father should be young and ill-fed, while the mother should be of mature years and highly-fed. The order should be reversed to produce males."

The three phases of the theory are here consolidated, and certain it is that with this combination-however unnatural the conditions-marked and positive results can be obtained. M. Girou, at a meeting of the Agricultural Society of Séverac, France, so long ago as July, 1826, proposed to so divide a flock of some three hundred sheep into two parts, that a greater number of males or females, at the choice of the owner, should be produced from each. The proposition was accepted and the experiment made.

The half that was highly fed and had young rams produced females in the proportion of three to two males; the other portion was rather poorly fed, had rams of mature years, and produced three males to two females, substantially as was predicted. I shall have occasion frequently to refer to M. Girou, whose experiments-if not his conclusions-display the exercise of more common sense than can be found in most writers on this subject.

We may further quote on this point the following from the Medical Investigator of Chicago: "Whether sex is determined by nutrition or not, is what scientists are solving. The experiments of Mr. Meehan, Mrs. Treat, and M. Gentry, on plants, butterflies, and moths, show that a high grade of nutrition gives females, and a low grade males."

Again Quillet, an old author, presents the nutritive theory, in a somewhat modified form, in the following naint lines:

"Males are the strength and glory of a race,
And female issue viewed by some as base;
An error obvious, for good sense allows
That sex is best to whom the other bows.
But let us, leaving this debate, our theme
Pursue, and tell how wives with males may teem.

Those most are apt for males in whom there meet
Most of male vigour and the vital heat;
This the learned tell us, and experience shows
That manly thoughts to manly love dispose.
A bold, a gen'rous, and an easy mind
Assist the sex to propagate its kind;
That future hymens may not strive for boys
In vain, nor covet heirs with fruitless joys,
Reason directs, that in the choice of food
The parents carefully prepare their blood.

Rich meals for you, ye bridegrooms, Nature bids,
And thrilling draughts to cheer your wishing brides;
Sufficient for the nuptial joys the vine,

And lusty boys are got by gen'rous wine.

And you, ye wives, who with your husbands join
To pray for sons to prop an ancient line,
At meals with sparkling wine rejoice your souls,
And freely pledge 'em in the modest bowls.
Give to these precepts in thy heart a place,
And masculine expect thy promised race."

Respecting this theory I may again cite Darwin, Tho said: "It has often been supposed that the relative ages of parents determine the sex of offspring, and Professor Leuckart has advanced what he Considers sufficient evidence with respect to man and certain domesticated animals, to show that this 15 one important factor in the result.

All this testimony is far from being groundless; and undoubtedly some glimpses of the great law sought for are thus obtained, but that any one or all of these conditions constitute that law is quite untenable. These conditions do not provide any principle of self-adjustment, or balance, the absence of which is, of itself, fatal to any theory whatsoever. They explain none of the anomalies brought to light by the statistician; and generalization upon them is impossible, further than to state the simple fact that a few given combinations are found to produce certain results, in a majority of cases. No explanation whatever can be offered of the host of exceptions; and these require to be taken into account, and a theory to be satisfactory must explain them.

Any one interested in the subject may call to mind families with an excess of either boys or girls, and find, far more frequently than otherwise, that they are of the sex of the fleshier parent, no less than of the older one. Superficial observers may be willing to rest upon these facts quite contented, but the further one looks the more numerous do the contradictions become. M. Girou, who left no stone unturned in his search for this law, settled downfor want of a better theory-upon that of comparative vigour; but it did not satisfy him. He discovered many facts which were in direct antagonism with it.

The following is such a perfect disproof of the physical vigour hypothesis that it would be a decided omission not to insert it; and best of all, it belongs to a class of facts which we can see verified all

around us every day of our lives: M. Girou obtained statistics from physicians, of eighteen consumptive mothers, who gave birth to eighty-seven children. Upon the basis of vigour, most of these should certainly be boys; but no, seventy-four were girls and only thirteen boys-one-seventh. Any reader can notice that such is about the usual proportion under similar circumstances. M. Girou estimates that of strong, athletic fathers, and feeble, delicate mothers, twenty daughters are born to one son. As these facts are fatally opposed to the only hypothesis he could devise, these statements by him show the commendable impartiality of the man.

I think it will be clear from the foregoing that physical superiority, or vigour, is not the sole or even preponderant determining cause of sex; but an examination of its influence upon the actual casting of the sex, together with the several other related phenomena, will be given in another chapter. A corollary from this theory of physical vigour gives, as mentioned above, the difference of age of the parents as the determining cause of sex, it being presumed that the elder parent is the more vigorous because more mature. This idea, however, was mainly due to the fact that in cases of any great difference in the ages of the parents, the children are observed to be chiefly of the sex of the elder parent. Thus Charles Roberts, F.R.C.S., in an article in the Lancet of December 11th, 1880, says that "we have statistics to prove that there should be a considerable difference in favour of the age of the husband if male progeny is desired." And all kinds of statistics have been compiled to show some point

in favour of this theory of physical vigour; as, for example, taking the proportion of the sexes in first births only, and also in the first five years of marriage as compared with the second, and so on; but apart from the fact that the statistics of early and late marriages have been included, and are thus vitiated ab initio, they fail to carry conviction owing to the number of contradictions thus brought out. Of these some idea may be gained from the above citations from Girou and others, but I shall be able to reconcile them by the true theory.

Some striking statistics-which are frequently quoted in support of this relative age theory—are given by Hofacker and Sadler, the important point brought out for the supporters of the theory of physical vigour being, that in each case there is an excess of children of the sex of the older and more mature parent. These figures show the proportion of male live births to every 100 females :