of Edinburgh, Session 1863-64. 
225 
4. On the Variations of the Fertility and Fecundity of 
Women according to Age. By Dr J. Matthews Duncan. 
This paper was divided into four parts. In the first part it was 
shown : — 
1. That the actual, not the relative, fertility of our female popu- 
lation, as a whole, at different ages, increases from the commence- 
ment of the child-bearing period of life until the age of 30 is 
reached, and then declines to its extinction with the child-bearing 
faculty. 
2. That the actual fertility is much greater before the climax, 
30 years, is reached, than after it is passed. 
3. That at least three-fifths of the population are recruited from 
women not exceeding 30 years of age. 
In the second part it was shown : — 
1. That comparative fertility increases gradually from the com- 
mencement of the child-bearing period of life until about the age of 
30 years is reached, and that then it still more gradually declines. 
2. That it is greater in the decade of years following the climax 
of about 30 years of age than in the decade of years preceding the 
climax. 
In the third part it was shown : — 
1. That the fecundity of the mass of wives in our population is 
greatest at the commencement of the child-bearing period of life, 
and after that epoch gradually diminishes. 
2. That the fecundity of the whole wives in our population in- 
cluded within the child-bearing period of life is, before 30 years of 
age is reached, more than twice as great as it is after that period. 
3. That the fecundity of the wives in our population declines 
with great rapidity after the age of 40 is reached. 
In the fourth part it was shown : — 
1. That the initial fecundity of women gradually waxes to a 
climax and then gradually wanes. 
2. That initial fecundity is very high from 20 to 34 years of age. 
3. That the climax of initial fecundity is probably about the age 
of 25. 
