Roscoe Wilfred Thatcher

“ Hence, much larger proportions of some elements than of others are taken from the soil by plants. The proportions of the different elements which are used by plants as raw materials for the manufacture of the products needed for their growth varies with the different species; but a certain amount of each of the so-called "essential elements" (see below) is necessary to every plant, because each such element has a definite rôle which it performs in the plant's growth. A plant cannot grow to maturity unless a sufficient supply of each essential element comes to it from the soil. ”

“ The ultimate material into which organisms are resolved by this process of biological analysis is the cell protoplasm. But protoplasm is itself made up of a complex system of definite chemical compounds, which react and interact according to the laws of physical science. Hence, any study of the chemistry of plant growth is essentially a study of the chemical and physical changes which take place in the cell protoplasm. ”

“ It requires no great stretch of the imagination to conceive that similar studies of plant life might result in similar or even greater benefit to human life, or society, since it is upon the results of plant growth that we are dependent for most of our food, clothing, and fuel, as well as for many of the luxuries of life. ”

“ Furthermore, the plant organism has acquired, by the process of evolution, the ability not only to produce an embryo for a successive generation but also to store up, in the tissues adjacent to it, reserve food material for the use of the young seedling until it shall have developed the ability to absorb and make use of its own external sources of food material. So that, finally, every study of plant chemistry must take into consideration the stored food material and the germinative process whereby this becomes available to the new organism of the next generation. ”

“ But for most, if not all, of the common farm crops whose possibilities in these respects have been studied, it has been found that a unit of nitrogen taken up as a nitrate is very much more effective in promoting growth, etc., than is the same unit of nitrogen in the form of ammonium salts.
While the proteins are finally stored up largely in the seeds, or other storage organs, they are actively at work during the growing period in the cells of the foliage parts of the plant. Hence, the popular statement that "nitrogen makes foliage" is a fairly accurate expression of its rôle. ”

“ It is wholly inconceivable that a homogeneous mass of all the varying chemical compounds which are contained in any given quantity of protoplasm could either exist or produce any regular sequence of chemical reactions. Structure, or organization of the cell-contents into separate colloidal compartments, and the segregation of cell-contents into masses having different functions, is essential to any reasonable conception of how the cell performs its various activities. ”

“ It is clear that this form of "morphological adaptation" is a highly specialized one, which can only be the result of a long process of evolutionary development. It is obvious that the plant cannot possibly possess a mechanism, or ability, to alter its flower form in order to make it conform to the shape and length of the proboscis, or other body parts, of a particular species of insect. Either the insect or the plant, or both, must go through a process of evolutionary development in order to arrive at this form of mutual "adaptation." ”

“ The substance upon which the enzyme acts (or, strictly speaking, the substance whose hydrolysis, oxidation, or other chemical change, is catalytically affected by the enzyme) is called the substrate.
Most enzymes are catalysts for hydrolysis reactions and are, hence, classed as hydrolytic in their action, and may be spoken of as "hydrolases." Those which accelerate oxidation are called "oxidases"; while those that stimulate reduction reactions are "reductases"; those that aid in the splitting off of ammonia, or amino-acid groups, are "deaminases" ”

“ Enzymes are present in all living matter. In animal tissues, they occur in the largest amounts in those glands or organs where active vital processes take place, as in the brain, the digestive tract, blood, etc. In plants, they may be found in all living cells, and are especially abundant in the seeds, where they serve to render soluble and available to the young plant the stored food materials. The enzymes of moulds, and other parasitic plants, are usually extracellular in type, being secreted for the purpose of making the material of the host plant available to the parasite. ”

“ Water is often a limiting factor in plant growth. Experiments which have been repeated many times and under widely varying conditions show that when water is supplied to a plant in varying amounts, by increasing the percentage of water in the soil in which the plant is growing by regular increments up to the saturation point, the growth of the plant, or yield of the crop, increases up to a certain point and then falls off because the excess of water reduces the supply of air which is available to the plant roots. ”

“ But the general significance of the term "autotrophic plants" is apparent.
"Heterotrophic plants" must, of necessity, get food, either directly or indirectly, from some other plant which can synthetize synergic foods or, in a few cases, from animal organic matter. If they do this by feeding upon the organic compounds of other living organisms, they are known as "parasites"; while if they secure their organic food from the tissues or debris of dead organisms, they are called "saprophytes." The heterotrophic plants are chiefly the bacteria and fungi ”

“ There is, as yet, no conclusive evidence on many of the matters concerning the relation of vitamines to plant growth. But it seems that these substances are of almost universal occurrence in the organic world; that they are not of the same general type as other substances which are essential to the nutrition of plants or animals, but have specific stimulating or regulating effects upon the physiological activities of the organism ”

“ The common conception that plant life and animal life are antithetical or complementary to each other has much to justify it. Animals breathe in oxygen and exhale carbon dioxide; while plants use the carbon dioxide of the air as a part of the raw material for photosynthesis and exhale oxygen. Plants absorb simple gases and mineral compounds as raw food materials and build these up into complex carbohydrates, proteins, fats, etc. ”

“ In the present state of our knowledge concerning the functioning of the proteins, no significance in the physiology of plant life, or metabolism, is to be attached to the particular type of protein material which it contains, at least so far as the simple proteins of the cytoplasm are concerned. ”

“ To avoid this confusion, the suggestion has recently been made that all of the intake of plants and animals shall be considered as food, but that those forms which supply both materials and potential energy to the organism shall be designated as synergic foods, while those which contain no potential energy shall be known as anergic foods. On this basis, practically all of the food of animals, excepting the mineral salts and water, and all of the organic compounds which are synthetized by plants and later used by them for further metabolic changes, are synergic foods ”

“ ACTIVATORS AND INHIBITORS
The activity of enzymes is strongly influenced by the presence in the solution of other bodies, usually, although not always, electrolytes. This is probably due, in most cases at least, to the action of the electrolyte upon the colloidal condition of the enzyme. All enzymes do not respond alike to the action of the same electrolyte, however. The activity of certain enzymes is enormously increased by the presence of a small amount of acid; while the action of another may be absolutely inhibited by the same acid in the same concentration. ”

“ The type of adjustment to environmental conditions which does not result in any recognizable alteration in the structure of the plant, but simply permits it to grow under new conditions, manifests itself in many ways. These adjustments are usually associated with differences in temperature during the growing season, and for this reason, most such examples of adaptation have been studied in connection with possible temperature reactions upon the growing organism. ”