136 INDUSTRIAL REVOLUTION AND WAGES 
American Association for Advancement of Science, 
December 29, 1917. He stated: 
It is obvious that the basis of every family is two 
individuals. The question then resolves itself as 
follows: How many children must be born to every 
family in order that two individuals may be raised 
to maturity? The number of children born must be 
more than two for a number of reasons. The first 
is the fact of mortality. The death rate is excep- 
tionally high in the period of childhood, amounting 
in the first year of life to about 10 per cent. of the 
babies born. If we begin with 100,000 at birth and 
trace them through from year to year, we find that 
about 75,000 are alive at the average age of marri- 
age. This is according to the mortality rate that 
prevails over a large portion of the United States. 
The rest have died. This fact alone would make it 
necessary that every marriage result in an average 
of two and one-half children in order that two per- 
sons may attain the average age of marriage and 
replace their parents in the population. But this 
assumes, first, that all persons marry, and, second, 
that every marriage is productive. As a matter of 
fact, all persons do not marry. In our own country 
from 12 to 15 per cent. do not marry until after the 
reproductive period, if at all. A considerable pro- 
portion of marriages, over 7 per cent. are sterile, 
When we make the necessary corrections in our fig- 
ures, the average number of children per family 
which must be born is increased to close to four in 
order that the stock may maintain itself without 
increase or decrease. 
The United States Bureau of Labor Statistics, the 
Chicago Council of Social Agencies, and other respon- 
sible authorities also gave official approval to this 
statement of Doctor Dublin.