acid is a product of oxidation in living cells, and has strong poisonous properties.  To get rid of it, the chemist inside the body, by the aid of calcium salts, forms insoluble compounds of it, and thus casts it out.  To separate substances from each other by filtration, or by shaking with suitable liquids, is one of the daily tasks of the chemist.  Analogous processes occur regularly in living cells.  Again, when the chemist wishes to finish his filtration quickly, he uses filters which have a large surface.  “In living protoplasms, this condition is very well fulfilled by the foam-like structure which affords an immense surface in a very small space.”  In the laboratory the chemist mixes his substances by stirring.  The body chemist achieves the same result by the streaming of protoplasm.  The cells know what they want, and how to attain it, as clearly as the chemist does.  The intelligence of the living body, or what we must call such for want of a better term, is shown in scores of ways—­by the means it takes to protect itself against microbes, by the antitoxins that it forms.  Indeed, if we knew all that our bodies know, what mysteries would be revealed to us!

IV

Life goes up-stream—­goes against the tendency to a static equilibrium in matter; decay and death go down.  What is it in the body that struggles against poisons and seeks to neutralize their effects?  What is it that protects the body against a second attack of certain diseases, making it immune?  Chemical changes, undoubtedly, but what brings about the chemical changes?  The body is a colony of living units called cells, that behaves much like a colony of insects when it takes measures to protect itself against its enemies.  The body forms anti-toxins when it has to.  It knows how to do it as well as bees know how to ventilate the hive, or how to seal up or entomb the grub of an invading moth.  Indeed, how much the act of the body, in encysting a bullet in its tissues, is like the act of the bees in encasing with wax a worm in the combs!

What is that in the body which at great altitudes increases the number of red corpuscles in the blood, those oxygen-bearers, so as to make up for the lessened amount of oxygen breathed by reason of the rarity of the air?  Under such conditions, the amount of haemoglobin is almost doubled.  I do not call this thing a force; I call it an intelligence—­the intelligence that pervades the body and all animate nature, and does the right thing at the right time.  We, no doubt, speak too loosely of it when we say that it prompts or causes the body to do this, or to do that; it is the body; the relation of the two has no human analogy; the two are one.