Biotech Core

Even the most casual perusal of many of its chapters cannot fail to make clear how incomplete is our present knowledge of the chemical changes by which the plant cell performs many of the processes which result in the production of so many substances which are vital to the comfort and pleasure of human life. Studies of the chemistry of animal life have resulted in many discoveries of utmost importance to human life and health. 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. The material presented in the book has been developed from a series of lecture-notes which was used in connection with a course in "Phyto-chemistry" which was offered for several years to the students of the Plant Science Group of the University of Minnesota.

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EBOOK THE CHEMISTRY OF PLANT LIFE *** Produced by Bryan Ness, Jens Nordmann and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/Million Book Project) AGRICULTURAL AND BIOLOGICAL PUBLICATIONS CHARLES V. PIPER, CONSULTING EDITOR THE CHEMISTRY OF PLANT LIFE +--------------------------------------------------------------+ | | | McGraw-Hill Book Co. Inc.

A more recent, and much more satisfactory, explanation of the "antagonism" between mineral elements in their toxic effects upon plants, which has both theoretical and experimental confirmation, is that single salts disturb the colloidal condition (see Chapter XV) of the protoplasm of the plant cells in such a way as to destroy its permeability to nutrient substances, while mixtures of salts restore the proper state of colloidal dispersion and permit the normal functioning of the protoplasm. It is apparent from the above brief discussions that the rôle of the different soil elements as plant food, and their relations to the complex processes which constitute plant growth, afford an interesting and promising field for further study. References BRENCHLEY, WINIFRED E.--"Inorganic Plant Poisons and Stimulants," 106 pages, 18 figs., Cambridge, 1914. HALL, A. D.--"Fertilizers and Manures," 384 pages, 7 plates, London, 1909. HALL, A. D.--"The Book of the Rothamsted Experiments," 294 pages, 49 figs., 8 plates, London, 1905. HOPKINS, C. G.--"Soil Fertility and Permanent Agriculture," 653 pages, Chicago, 1910. HILGARD, E. W.--"Soils," 593 pages, 89 figs., New York, 1906. LOEW, O.--"The Physiological Rôle of Mineral Nutrients," U. S. Department of Agriculture, Bureau of Plant Industry, _Bulletin_ No. 45, 70 pages, Washington, D. C., 1903. RUSSELL, E. J.--"Soil Conditions and Plant Growth," 243 pages, 13 figs., _Monographs_ on Biochemistry, London, 1917.

There is, as yet, no satisfactory explanation of this difference in behavior between plant tissues toward various organic toxic substances. In fact, the whole subject of the toxic action of various substances upon plants needs much more study before it is brought to the point where it will afford definite knowledge of either the physiological problems involved or of their practical applications in questions of soil productivity, etc. CHAPTER XVIII ADAPTATIONS Most of the discussions which have been presented in the preceding chapters have dealt with the types of compounds, the kinds of reactions, and the mechanism for the control of these, which are exhibited by plants under their normal conditions for development. The results of the evolutionary process have produced in the different species of plants certain fixed habits of growth and metabolism. So definitely fixed are these that in each particular species of plants each individual differs from other individuals, which are of the same age and have had the same nutritional advantages and environmental opportunities for growth, by scarcely perceptible variations, if at all. Indeed, this fixed habit of development makes possible the classification of plants into genera, species, etc.