thus cutting off the supply of nutrition. The cells of tumors peculiar
to man show a narrow range of adaptation. They will grow only in the
body of the individual to whom the tumor belongs, and die when grafted
on another individual. In the case of tumors which arise in animals,
pieces of the tumor when grafted on another animal of the same species
will grow, and in this way the growth capacity of the tumor cells has
been estimated. Thus, by transplanting a small section of a mouse
tumor into other mice, the small transplanted fragments will in two
weeks grow to the size of filberts, and each of these will furnish
material to engraft upon ten mice. These new tumors are similar in
character to the original tumor, and really represent parts of it in
the same way that all the Baldwin apples in the world are parts of the
original tree which was found in Baldwinville many years ago, and as
all the Concord grape vines are really parts of the original vine. It
has been estimated that if all the growth capacity of this mouse tumor
were availed of by the successive inoculation of other mice, a mass of
tumor several times the diameter of the sun would grow in two years.
The condition of the individual seems to exert no influence upon the
growth of the tumor. Growth may be as rapid when the bearer is in a
condition of extreme emaciation as it is when the bearer is well
nourished and robust.

[Illustration: FIG 14.--PHOTOGRAPH OF A MICROSCOPIC PREPARATION FROM A
CANCER OF THE UTERUS. A large mass of cells is extending into the
tissue of the uterus which is shown as the fibrous structure. Such a
cell mass penetrating into the tissue represents the real cancer, the
tissue about the cell masses bear the blood vessels which nourish the
tumor cells.]

Those tumors which grow rapidly and invade and destroy the surrounding