Page:The Harveian oration 1912.djvu/17

Rh that the individual cell is the master of the situation, and that the dominant issue that comes up is: What is there in that cell or influencing it that gives to it such an inexhaustible power of propagation? whence comes that boisterous energy of which I have spoken?

So in this quarter of study, as in others I must mention, we seem to have come to what is still but a mirage, to an inaccessible land, where histology perhaps may no further help, and where organic chemistry and physics must take up the running, and show what part they play in the origin of life; or if not that, we must search for and find the homologue of cancer in some still more embryonic stage of existence and inquire of its habits there.

Thus what we call pathology is growing up. But are we sufficiently alive to the fact that it is no series of stationary phenomena, but constantly on the move, like all else in Nature, and in being so shifts its ground?

That it changes absolutely you will, I think, readily admit. As I think of disease in the post-mortem room forty years ago, what alterations have we not seen! Pyæmia may be said to be wiped out; typhus is wellnigh forgotten; typhoid fever has altered; diphtheria seldom attains the initial severity that so often characterized it of yore, and is much more amenable to our attack; scarlatina is of a