These catalytic reäctions soon became very important factors in organic chemistry and biology, as well as in the field of inorganic chemistry. In 1833, Payen and Persoz in Paris made the discovery that germinating seeds contain a peculiar contact-substance, which transforms starch into sugar. This substance they named _Diastase_. Similar effects were noted to occur elsewhere,--particularly in the protein digestion in the stomach of man and the higher animals. We now know that many such reäctions occur in the living cells, and the chemical phenomena of life have had an entirely new light thrown upon them by these findings. ENZYMES They led, in short, to the discovery of the so-called _Enzymes_. Until relatively recently, the expression “Ferment” was used, as the phenomena were akin to fermentation. Soluble ferments are termed Enzymes, and the phenomena connected with living protoplasm are now known to be largely due to the action of a group of Enzymes. These are catalytic substances, are of a limited field of action, of colloidal nature, and very little resistant to heat. When injected into the veins of animals, other substances are at once manufactured, which have been called “anti-enzymes,” which have the effect of offsetting their action. Sunlight and ultra-violet light destroy enzymes. Their importance in the field of biology may be discerned when it is stated that researches have shown us that, _e. g._, the amount of protein digested in a certain time is not proportional to the quantity of the enzyme itself, but to the square root of the quantity of the enzyme. HORMONES These enzymes must not be confused with other internal secretions, such as the _hormones_. These are substances generated by the so-called ductless glands,--such as the thyroid, the pituitary, the adrenals, etc. These ductless glands secrete substances which when absorbed into the blood-stream greatly affect the life of the body, its functions, its structure and its growth, and to a certain extent at least the mental life. Researches in this field are of relatively recent origin, but of extreme importance. I have mentioned this subject at greater length in my little book on “Life: Its Origin and Nature,” in the present series, and the interested reader may refer to such a work as Dr. Louis Berman’s “The Glands Regulating Personality,” for further details. There is no matter anywhere in the universe, living or dead, which modern chemistry does not attempt to analyze. Not only in the laboratory are these tests undertaken, with minute particles of matter. The very earth on which we dwell has been subjected to chemical analysis, and so have the stars, the planets and suns which circle around us in space,--perhaps separated from us by many millions of miles. The ability to do this is assuredly one of the greatest achievements of the mind of man, and represents one of the greatest conquests over nature, over time and space. CHEMISTRY OF THE EARTH