tions of the heart of the child in the womb are counted,--as can
easily be done by a practised medical ear during the last months of
pregnancy,--and are found to be over one hundred and thirty in a minute,
it is a daughter; if under one hundred and thirty, a son. In this
manner, the sex of an unborn child can be predicted with tolerable
accuracy, excepting only when illness of the foetus has deranged the
action of its heart.

ARE THERE TWINS PRESENT?

Certain signs lead to the suspicion of twins, such as being unusually
large, and the fact that the increase in size has been more than
ordinarily rapid. Sometimes also the abdomen is divided into two
distinct portions by a perpendicular fissure. In other cases the
movements of a child can be felt on each side at the same time. And in
twin pregnancies the morning sickness is apt to be more distressing, and
all the other discomforts incident to this condition increased. But
these signs and symptoms, when present in any given case, are not
conclusive, for they may be noticed when there is only one child. The
doctor has one characteristic and infallible sign by which he can
ascertain whether the woman be pregnant with twins. It is furnished to
him again by the art of listening,--or auscultation, as it is
technically called,--the same that, as we have already seen, may enable
him to determine the sex of the child. When the beatings of two foetal
hearts are heard on opposite portions of the abdomen, the nature of the
pregnancy is apparent.

LENGTH OF PREGNANCY.

What is the ordinary duration of pregnancy? Almost every woman considers
herself competent to make the answer--nine months. She may be surprised
to learn, however, that such an answer is wanting in scientific
precision. It is too indefinite, and is erroneous. There is a great
difference between the calendar and the lunar month. Each lunar month
having twenty-eight days, the period of nine lunar months is two hundred
and fifty-two days. Nine calendar months, including February, represent,
on the contrary, two hundred and seventy-three days. Now the average
duration of pregnancy is two hundred and eighty days, that is forty
weeks, or ten lunar months.

While most extended observations have shown that as a general rule,
forty weeks, or two hundred and eighty days, is the true period of
pregnancy, are we justified in the conclusion that this is its
invariable duration? This important question, upon the answer to wh