476 DR MATTHEWS DUNCAN ON THE VARIATIONS OF THE FERTILITY 



tion my obligations to the various intelligent and assiduous gentlemen who have 

 assisted me in the work. 



The part of my investigations which is the subject of this communication is 

 confined to the determination of the comparative fertility or productiveness and 

 fecundity of women at different ages. It is necessary, in order to avoid confusion, 

 here to establish a distinction, which I shall maintain as I go on, between fer- 

 tility or productiveness and fecundity. By fertility or productiveness I mean the 

 amount of births as distinguished from the capability to bear. This quality of 

 fertility or productiveness is interesting chiefly to the statistician or the political 

 economist. It does not involve the capability of every individual considered to 

 bear, nor even the conditions necessary for conception. By fecundity I mean the 

 capability to bear children ; it is measured by the number born, and it implies 

 the conditions necessary for conception in the women of whom its variations 

 are predicated. This quality of fecundity is interesting chiefly to the phj^siologist 

 and physician. 



In discussing the subject of comparative fertility and fecundity at different 

 ages, I may incidentally afford means for estimating the degree of fertility or 

 fecundity of different ages ; but I wish it to be distinctly understood, that I have 

 not proposed to myself, in this paper, the consideration of the actual degree or 

 amount of fertility or fecundity at any age, but only the variations of fertility or 

 fecundity at different ages as compared with one another. 



Chapter L — The Actual Fertility of our Female Population as a whole at 



Different Ages. 



The first law which I propose to establish, has reference to the ages of the 

 mothers of legitimate children. In Edinburgh and Glasgow legitimate births 

 form at least 90 per cent, of the whole born. The law, therefore, regards the 

 ages of the women from whose fertility 90 per cent, of the population are 

 recruited. 



It must be observed, that this law or general statement shows nothing re- 

 garding the fecundity of women of different ages, although it has been held as 

 doing so ; it merely enunciates a truth in the doctrine of population. I place 

 it first because it is pretty well known, because in my own investigations it was 

 first made out, and chiefly because it is essential, before proceeding farther, to 

 show the facts on which it is founded in their true light, avoiding the great errors 

 of which they have been made the basis.* 



The facts or data illustrating this law, with which I am best acquainted, have 

 been derived from reports of lying-in dispensaries, as by Dr Granville, or from 

 similar accounts of lying-in hospitals, as by Dr Collins, Drs Hardy and M'Clin- 



* See Granville, Transactions of Obstetrical Society of London, vol. ii. 



