The powers of living matter are still more characteristic. It is continually wasting away by a kind of internal combustion, but continually repairs the waste by the processes of growth.

Moreover, this growth is of a characteristic kind, differing absolutely from the so-called growth of lifeless things. Crystals and other lifeless bodies grow, if at all, by accretion, or the addition of new particles to the outside. Living matter grows from within by intus-susception, or taking in new particle...