ances prove fatal. Sir Astley Cooper mentions two cases in
which terror instantaneously and permanently arrested this secretion. It
is also affected by the food and drink. Malt liquors and other mild
alcoholic beverages temporarily increase the amount of the secretion,
and may, in rare instances, have a beneficial effect upon the mother.
They sometimes affect the child, however, and their use is not to be
recommended unless the mother is extremely debilitated, and there is a
deficiency of milk.

* * * * *

CHAPTER XI.

PHYSIOLOGICAL ANATOMY.

EXCRETION.

The products resulting from the waste of the tissues are constantly
being poured into the blood, and, as we have seen, the blood being
everywhere full of corpuscles, which, like all living things, die and
decay, the products of their decomposition accumulate in every part of
the circulatory system. Hence, if the blood is to be kept pure, the
waste materials incessantly poured into this fluid, or generated in it,
must be as continually removed, or excreted. The principal sets of
organs concerned in effecting the separation of excrementitious
substances from the blood are the lungs, the skin, and the kidneys.

The elimination of carbonic acid through the lungs has already been
described on page 66, and the excretory function of the skin on page 70.

[Illustration: Fig. 53.
View of the kidneys, ureters, and bladder. ]

The kidneys are two bean-shaped organs, placed at the back of the
abdominal cavity, in the region of the loins, one on each side of the
spine. The convex side of each kidney is directed outwards, and the
concave side is turned inwards towards the spine. From the middle of the
concave side, which is termed the _hilus_, a long tube of small caliber,
called the _ureter_, proceeds to the bladder. The latter organ is an
oval bag, situated in the pelvic cavity. It is composed principally of
elastic muscular fibers, and is lined internally with mucous membrane,
and coated externally with a layer of the _peritoneum_, the serous
membrane which lines the abdominal and pelvic cavities. The ureters
enter the bladder through its posterior and lower wall, at some little
distance from each other. The openings through which the ureters enter
the bladder are oblique, hence it is much easier for the secretion of
the kidneys to pass from the ureters into the bladder than for it to get
the other way. Leading from the bladder to t