egnancy will take place.
On the contrary, there are well-authenticated cases of women who were
stout and barren in opulence becoming thin and prolific in poverty.

The stimulus of novelty to matrimonial intercourse imparted by a short
separation of husband and wife, is often salutary in its influence upon
fertility.

To show upon what slight constitutional differences infertility often
depends, it is merely necessary to allude to the fact, known to every
one, that women who have not had children with one husband often have
them with another. This condition of physiological incompatibility is
evidently not altogether one of the emotional nature, for it is observed
in animals, among whom it is by no means rare to find certain males and
females who will not breed together, although both are known to be
perfectly fruitful with other females and males. The ancients, believing
that sterility was more common with couples of the same temperament and
condition, advised, with Hippocrates, that blonde women should unite
with dark men, thin women with stout men, and _vice versa._

Barren women should not despair. They sometimes become fecund after a
long lapse of years. In other words, they are sterile only during a
certain period of their lives, and then, a change occurring in their
temperament with age, they become fruitful. History affords a striking
example of this eccentricity of generation, in the birth of Louis XIV.,
whom Anne of Austria, Queen of France brought into the world after a
sterility of twenty-two years. Catherine de Medicis, wife of Henry II.,
became the mother of ten children after a sterility of ten years. Dr.
Tilt, of London, mentions the case of a woman who was married at
eighteen, but although both herself and her husband enjoyed habitual
good health, conception did not take place until she was forty-eight,
when she bore a child. Another case is reported where a well-formed
female married at nineteen, and did not bear a child until she had
reached her fiftieth year.

Families often suffer from the effects of sterility. Civilised nations
never do. Recent researches have been carefully instituted in several
countries to determine the exact power of the human race to preserve its
numbers against the ravages of death. It has been ascertained that
during periods of peace the population can be maintained to the same
point by the additions made to it through the procreating capacity of
only one-half of the wome