490 ON THE FERTILITY AND FECUNDITY OF WOMEN, ETC. 



animals. This annual variation forms a series of wavelets in the course of the 

 great wave running from youth to old age, and culminating in middle life. This 

 annual rise and fall of fecundity he attributes to the influence of cold. 



In his " Treatise on Man," M. Quetelet has, with some care, collected the 

 statistical materials available at the time for advancing the settlement of the 

 question of the relation of age to fecundity. He does not allude to the opinions 

 of BuRDACH, probably because they have no sufficient foundation, but he refers to 

 Milne, Malthus, Sadler, Granville, Finlayson, and several foreign authors, 

 who have more or less directly tried to throw light on the topic. Quetelet's 

 whole chapter on the influence of age on the fecundity of marriages is very un- 

 satisfactory. It is at least difficult to reconcile with one another the conclusions 

 arrived at in various parts of this chapter, and I shall not attempt to do it. It 

 is only fair to say, that he seems conscious of the numerical deficiency of data 

 sufficient for a basis of any conclusion, and as an example of the state of matters, 

 the table of Sadler, which he and Burdach both quote, may be mentioned ; in it 

 the number of marriages analysed is under 500, and they are all selected accord- 

 ing to extraordinary conditions. The final conclusion which M. Quetelet an- 

 nounces is, that it is before the age of 26 years that we observe the greatest 

 fecundity in women. 



The last writer on this topic whom I know of is Dr Granville, who, in an 

 interesting paper in the London Obstetrical Transactions, returns to the descrip- 

 tion of his former labours in the same field. In this paper, production or fertility 

 is confounded Avith productive power or fecundity, and the table to which I 

 have alluded in Chapter I. he describes not as showing the fertility at different 

 ages of the industrial classes of the metropolis, but erroneously, as showing the 

 alternations in the productive power of women at different ages. 



In this paper, then, I have, inter alia, shown that the great majority of the 

 population is recruited from women under 30 years of age ; but that the mass 

 of women in the population, of from 30 to 40 years of age, contribute to the 

 general fertility a larger proportional share than the mass of women of from 20 

 to 30 years of age : — 



Further, that the wives in our population, taken collectively as a mass, show 

 a gradually decreasing fecundity as age advances; but that the average individual 

 wife shows a degree of fecundity which increases till probably about the age of 

 25, and then diminishes. 



The fertility of the average individual woman may be described as forming a 

 wave which, from sterility, rises gradually to its highest, and then, more gradu- 

 ally, falls again to sterility. 



