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growths in the larynx, but is by no means such an artistic production as the monograph we have just considered. It bears traces of having been written at an earlier date, and before the author's views had ripened into the full excellence displayed in his larger treatise. The other chapters on throat affections are well done, and some of them strike us as being exceptionally good, but all are too much condensed. The space allowed was evidently too limited to enable the author to do justice, either to his subject or to himself. We regret this because Dr. Mackenzie is eminently qualified to write well on diseases of the larynx. With greater space at his command, he would have made his contribution, good as it is, much better. The ill luck, to call it by no stronger term, of the System of Medicine' is remarkable. Every new volume brings some fresh disappointment. The authors best qualified to write find little space or none, and some who write with small authority occupy great space. If in this third volume fifty more pages, which might well have been cut off some of the other articles, had been allotted to the larynx, Dr. Reynolds would have issued a volume more fitted to meet our present needs.

V. Dr. M. Duncan on Fertility and Fecundity.1

Dr. Duncan's work may be described as a statistical inquiry into certain obstetrical subjects. Figures form the basis of his work, and, therefore, in the very nature of things, a wide field for controversy is opened. But it must be said that his opponents will find considerable difficulty in refuting the arguments advanced in this able work, though they may find grounds for divergence of opinion.

The work is divided into ten parts, the first of which alone is devoted to the subject from which it takes its title. This, however, is the most elaborate portion of the volume, and one with which it is most difficult to deal, either critically or analytically. It is based, as Dr. Duncan avows, almost exclusively on a considerable mass of figures. That figures may be used very differently, according to the bias of the manipulator, and that very conflicting conclusions may be drawn from the same statistical data is notorious. This volume forms no exception to that rule, though, in justice to Dr. Duncan, it must be said that he has very fairly and with great ability handled

1 Fecundity, Fertility and Sterility, and Allied Topics. By J. MATTHEWS DUNCAN, A.M., M.D. Second edition, revised and enlarged. Edinburgh, A. and C. Black, 1871. Pp. 498.

the materials at his command. We have some difficulty, however, in accepting all his conclusions.

With reference to the data used in Part I, it may be remarked that they comprise 16,593 children, legitimately born in Edinburgh and Glasgow in the year 1855. These figures, however, are but for one year only, and that, as Dr. Duncan shows, an exceptional one, fortunately for his purpose, as regards the mode of registration, which was only in force during the year in question. It may be urged that other years, that other towns, and, à fortiori, rural districts would have yielded different results. Clearly this might have been so; we have, however, to deal with the material before us.

Dr. Duncan appears to be alive to the "difficulty of handling statistics without infringement of the rules of logic," and he declares that he was all the more careful in dealing with his subject, owing to the necessity of pointing out great errors made by other authors.

Before entering upon the subject of the first part, Dr. Duncan points out that it is necessary, to avoid confusion, to establish some amount of distinction between fertility or productiveness and fecundity.

"By fertility or productiveness I mean the amount of births as distinguished from the capability to bear..... By fecundity I mean the demonstrated capability to bear children.

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In the first chapter the author treats upon the actual fertility of the female population as a whole at different ages. He uses Dr. Collins's statistics, showing the age of each 16,385 women delivered in the Dublin Lying-in Hospital, these women being mothers of legitimate and illegitimate children, live and dead, and his own statistics, showing the age of each of 16,301 wives, whose children were all born alive, and registered in Edinburgh and Glasgow in 1855.

It is necessary to point out that these two sets of statistics are not quite on the same level. It may fairly be urged in the interest of Dr. Collins's statistics, that while his gross numbers are almost identical with those of Dr. Duncan, and, therefore, equal in that respect, they are, as regards both mothers and children, more comprehensive, embracing as they do, of the former, the unmarried as well as the married, and of the latter, the dead as well as the living. However true Dr. Matthews Duncan's deductions may be as regards his own statistics, which it will be observed deal only with married mothers of living children, they can hardly be held to invalidate the more broadly based statistics of Dr. Collins, which deal with married and single mothers and with living and dead children. Therefore Dr. Duncan's conclusions cannot be held to override those of Dr.

Collins; and, as an additional argument in favour of the latter, it may be urged that the statistics of motherhood in the married cannot truly exhibit either the fertility or fecundity of females; since many women capable of bearing children are unable, for social reasons, to marry until some years after that capability has existed; and, therefore, statistics showing the fertility of both the married and unmarried are much more likely to display the true fertility of women than those which are confined to the married.

After all, Dr. Duncan agrees with Dr. Collins that most children are born of women at or near the age of thirty years; and further, that more children are borne by women under thirty than by those above that age; but they differ as to the proportion, Dr. Duncan showing it to be, according to his own data, about three fifths, while Dr. Collins, from his data, calculates it to amount to three fourths.

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To the reasoning contained in Chap. II we are constrained to take exception. In it the author proceeds to compute the Comparative Fertility of the Female Population as a Whole at different Ages," on data which are obviously insufficient, not to say fallacious. To arrive at the desired result, Dr. Duncan computes the comparative fertility of the whole female population of Edinburgh and Glasgow in 1861 by the standard of the married mothers of living children born in Edinburgh and Glasgow in 1855. In such a process as this assumptions have largely to be made, and to such a proceeding in a matter dealing with statistical data we really must demur.

Nothing should be assumed, nothing taken for granted in such questions; the figures alone should be dealt with-and these should in every possible respect correspond-as forming unalterable data for the discussion and decision of the points involved. Moreover, as already said, the figures should be for corresponding periods, else vitiating assumptions have to be made, and these, once admitted, invalidate the whole of the work.

The third chapter deals with "The Comparative Fecundity of the whole Wives in our Population at different Ages." To this chapter the objections advanced against the last do not apply, the comparison being, not of wives-mothers with women living, but of wives-mothers with wives. The first table in this chapter, however (Table VII), seems to disprove the statement made by Dr. Duncan, in the concluding sentence of the previous chapter, viz., that the fertility of the whole female population, at different ages, is greater in the decade following the climax of thirty years than in the decade preceding the age of thirty; for we see in this table that half the wives (50.00 per cent.)

between the ages of 15 and 19 bear children, 41-79 per cent. between the ages of 20 and 24, 34-64 per cent. between the ages of 25 and 29, 26.56 per cent. between the ages of 30 and 34, 20-39 per cent. between the ages of 35 and 39, 8.04 per cent. between the ages of 40 and 44, and 1.27 per cent. between the ages of 45 and 49.

It is clear, therefore, that both the fertility and the fecundity of wives-mothers under thirty greatly exceed that of the wivesmothers over thirty. This Dr. Duncan sees and admits in the following terms:-"The wives under thirty years of age were much more than twice as fecund as the wives above thirty years of age.' This admission agrees with the statement at page 21. "So far as they (the data) go, they indicate a great fecundity of a mass of wives at 17, 18, and 19."

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There is some difficulty, however, in reconciling these statements with one at page 17, to the effect that the comparative fertility of our whole female population, at different ages, is greater in the decade of years following the climax of about thirty years of age than in the decade of years preceding the climax. This would tend to show that fertility and fecundity are opposed to each other, which cannot be.

Chap. IV deals with the "Initial Fecundity of Women at Different Ages." This is a somewhat difficult subject to work, possible immaturity in some of the younger wives-and here Dr. Duncan deals only with the married-having to be allowed for; but from the data used Dr. Duncan concludes that the climax of initial fecundity is probably about the age of twentyfive years.

In the next chapter the "Fecundity of Women at Different Ages" is discussed, and here again Table XIV shows the percentage of fertile wives to be almost 100 per cent. between the ages of fifteen and twenty-four, being greatest between the twentieth and twenty-fourth years of age. According to Dr. Duncan's own tables, then, both fertility and fecundity would seem to be, as was remarked above, greater under than above thirty years of age. As bearing upon this subject, Dr. Duncan makes an interesting and valuable quotation from a work by Mr. Geyelin, C.E., on "Poultry-breeding in a Commercial Point of View," which he introduces with the remark that "a remarkable illustration of the variation of fecundity at different ages is acquired by observation of the fertility of the domestic fowl." Mr. Geyelin says that a hen cannot lay more than 600 eggs, the ovarium containing no more than that number of ovula. These are distributed over nine years, in a proportion which shows that by far the greatest share of them is laid before the commencent of the fifth year; and it follows, therefore, that

it would not be profitable to keep hens after their fourth year. Such evidence as is forthcoming tends to show that the best time for the procreation of strong and healthy children is, in women, from the age of about twenty-three to about thirty-three years.

Dr. Matthews Duncan candidly admits that this portion of his work has been adversely criticised, and that his friend Professor Tait's notes are not exactly consistent with his own views.

In Part II the author deals with the weight and length of the newly-born child, which subject he introduces with the following statement:

"Inquiring into the influence of the age of the mother upon fecundity, I desired to find out if any light could be thrown upon the subject by the variations, if any, of the weight and length of mature children born of women at different ages; intending to assume that the weight and length of the child might increase or diminish with the high or low state of the fecundity of women, or of the vigour of the generative functions."

Dr. Duncan's observations are based on 2070 pregnancies, yielding 2087 children, occurring in the practice of the Edinburgh Maternity Charity. Hecker's observations show that the weight of the children of multiparæ is slightly, though distinctly, in excess of that of the children of primiparæ, and Dr. Duncan's observations are, so far as they go, corroborative; but the latter also show what Hecker, from ignorance of the fact, did not, that the age of the mother, whether primiparous or not, influences the weight of her offspring. This is in accordance with what is known about cattle breeding; and those who are acquainted with this subject are aware that it is a matter of belief among breeders that a young heifer will not bear so fine a calf as a maturer breast. Dr. Duncan's tables indicate that mothers in the prime of life bear the heaviest children, and he thinks, rightly no doubt, that it is the maturer age of the mother, and not mere multiparity, to which this is to be attributed. But beyond the prime of life-say over the thirty-fifth year-it is thought that the primiparous woman bears a smaller child than she would have done had she been pregnant some six or eight years sooner, and that this accounts for the easier labours of old primiparæ than of primiparæ in the prime of life.

As regards the influence of primo-geniture on the length of the newly-born child, the author says that no notable difference is made out between the offspring of primiparæ and multiparæ; but, as far as the evidence goes, it is in favour of the former, whose children are a little longer than those of the latter.

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