It will be seen that, in general, "hormones" are a type of substances (possibly often present in plants in the form of glucosides) which are supposed to stimulate the degenerative (or katabolic) vital processes in contrast to the synthetic (or anabolic) changes. It has been suggested that they do this in either one of two ways; namely, by favoring the introduction of water into the protoplasm and so diluting the cell contents, changing the osmotic pressure, etc.; or by bringing about a separation of the colloidal layers, or films, of the protoplasmic complex, producing a result similar to that produced by freezing the tissues. These ideas have been suggested by studies of the changes in the equilibrium of protoplasm when foreign substances are introduced into it. These studies have not as yet been brought to the stage of final conclusions, and the ideas presented must be considered as suggestive rather than as conclusive. VITAMINES "Vitamines," as contrasted with "hormones," are supposed stimulants of synthetic metabolic processes, or accelerators of growth, rather than of degenerative processes. The term "vitamine" was first used to designate the substance, or substances, which must be present in the diet of animals in order that the animal organism may grow. Absence of these substances from the food of the animal results in the stoppage of growth of young animals and in various so-called "deficiency diseases" (such as beri-beri, scurvy, polyneuritis, etc.) of adults. This means that the animal organism is altogether unable to elaborate its own vitamines, and extended investigations have indicated that the vitamines necessary for animal uses are wholly of plant origin. The name "vitamine" was first used because it was supposed that these substances are chemical compounds of the amine type and, since they are necessary to normal life processes of animals, the name "vitamine" seemed to represent both their chemical character and their functions. Later investigations have caused doubt as to the accuracy of the first belief as to their chemical nature, and various other names have been suggested for the general group of substances which have the observed beneficial effects; while such specific names as "fat-soluble A," "water-soluble B," etc., have been used to designate individual types of these accessory food substances. However, the term _vitamine_ is such a convenient one and is so generally recognized and accepted that it will probably continue to be used, at least until some more definite knowledge of the nature and composition of these growth-promoting, disease-preventing, and reproduction-stimulating food constituents is obtained.