while these substances are found in some animals; while many animals
contain no horny matter and no gelatin-yielding substance. So that the
matter which appears to be the essential foundation of both the animal
and the plant is the proteid united with water; though it is probable
that, in all animals and plants, these are associated with more or
less fatty and amyloid (or starchy and saccharine) substances, and
with very small quantities of certain mineral bodies, of which the
most important appear to be phosphorus, iron, lime, and potash.

Thus there is a substance composed of water + proteids + fat +
amyloids + mineral matters which is found in all animals and plants;
and, when these are alive, this substance is termed protoplasm.

The wheat plant in the field is said to be a living thing; the fowl
running about the farmyard is also said to be a living thing. If the
plant is plucked up, and if the fowl is knocked on the head, they soon
die and become dead things. Both the fowl and the wheat plant, as we
have seen, are composed of the same elements as those which enter into
the composition of mineral matter, though united into compounds which
do not exist in the mineral world. Why, then, do we distinguish this
matter when it takes the shape of a wheat plant or a fowl, as living
matter?

In the spring a wheat-field is covered with small green plants. These
grow taller and taller until they attain many times the size which
they had when they first appeared; and they produce the heads of
flowers which eventually change into ears of corn.

In so far as this is a process of growth, accompanied by the
assumption of a definite form, it might be compared with the growth of