builds up and pulls down.  It integrates the rocks and, under changed conditions, it disintegrates them.  In the organic world chemical affinity is equally active, but it plays a subordinate part.  It neither builds up nor pulls down.  Vital activities, if we must shun the term “vital force,” do both.  Barring accidents, the life of all organisms is terminated by other organisms.  In the order of nature, life destroys life, and compounds destroy compounds.  When the air and soil and water hold no invisible living germs, organic bodies never decay.  It is not the heat that begets putrefaction, but germs in the air.  Sufficient heat kills the germs, but what disintegrates the germs and reduces them to dust?  Other still smaller organisms? and so on ad infinitum?  Does the sequence of life have no end?  The destruction of one chemical compound means the formation of other chemical compounds; chemical affinity cannot be annulled, but the activity we call vital is easily arrested.  A living body can be killed, but a chemical body can only be changed into another chemical body.

The least of living things, I repeat, holds a more profound mystery than all our astronomy and our geology hold.  It introduces us to activities which our mathematics do not help us to deal with.  Our science can describe the processes of a living body, and name all the material elements that enter into it, but it cannot tell us in what the peculiar activity consists, or just what it is that differentiates living matter from non-living.  Its analysis reveals no difference.  But this difference consists in something beyond the reach of chemistry and of physics; it is active intelligence, the power of self-direction, of self-adjustment, of self-maintenance, of adapting means to an end.  It is notorious that the hand cannot always cover the flea; this atom has will, and knows the road to safety.  Behold what our bodies know over and above what we know!  Professor Czapek reveals to us a chemist at work in the body who proceeds precisely like the chemist in his laboratory; they might both have graduated at the same school.  Thus the chemist in the laboratory is accustomed to dissolve the substance which is to be used in an experiment to react on other substances.  The chemical course in living cells is the same.  All substances destined for reactions are first dissolved.  No compound is taken up in living cells before it is dissolved.  Digestion is essentially identical with dissolving or bringing into a liquid state.  On the other hand, when the chemist wishes to preserve a living substance from chemical change, he transfers it from a state of solution into a solid state.  The chemist in the living body does the same thing.  Substances which are to be stored up, such as starch, fat, or protein bodies, are deposited in insoluble form, ready to be dissolved and used whenever wanted for the life processes.  Poisonous substances are eliminated from living bodies by the same process of precipitation.  Oxalic