trols the _tone_ of the tissues, of involuntary or smooth muscle
fibres of the blood vessels and the contractile organs of the body
like the intestines, the bladder and uterus. When injected, it will
slowly raise the blood pressure and keep it raised for some time, and
will increase the flow of urine from the kidneys and of milk from the
breasts. It will also cause an intense continued contraction of the
bladder and the uterus. It is also said to control the salt content of
the blood upon which its electrical conductivity and other properties
depend. Normally, there is a certain fixed ratio of the salts in the
blood, which keeps them like the ratio in sea-water. Again, we have
an example of the curious atavism of the internal secretions. The
thyroid, remember, keeps the iodine concentration of the blood like
that of the ocean, our original habitat. Pituitrin likewise does its
part to maintain our internal environment as near as possible to what
was once the surrounding medium. A substance somewhat similar has been
found in the skin glands of toads.

The extraordinarily well protected position of the pituitary, its
persistence throughout life, and its abundant blood supply, emphasize
its vital importance. No other gland of internal secretion can
adequately substitute for it. Complete expiration means death, in two
or three days, with a peculiar lethargy, unsteadiness of gait and loss
of appetite, emaciation, and a fall of temperature, so that the
animal becomes cold-blooded, its temperature the same as that of the
atmosphere it occupies. If only part of the anterior lobe is taken
away, there occurs a remarkable degeneration of the individual. The
degeneration is not a mucinous infiltration of the skin and the
internal organs which occurs with thyroid deprivation, but a fatty
degeneration, with a tendency to inversion of sex. A singular
somnolence, a dry skin, loss of hair, a dull mentality, sometimes
epilepsy, and a noticeable craving for and tolerance of sweets appear.
These are but a few of the observations obtained in experimental
sub-pituitarism, that is, underaction or insufficient secretion of the
pituitary, produced by removing part of the anterior gland.

If such an experimental sub-pituitarism is started in infancy, for
instance in puppies, there is a cessation, or marked hindering and
slowing of growth. That is, dwarfs are artificially created. Apropos,
pathologists have shown that in several true human dwarfs