File:Cyclopedia of American horticulture, comprising suggestions for cultivation of horticultural plants, descriptions of the species of fruits, vegetables, flowers, and ornamental plants sold in the (20538442818).jpg

Title: Cyclopedia of American horticulture, comprising suggestions for cultivation of horticultural plants, descriptions of the species of fruits, vegetables, flowers, and ornamental plants sold in the United States and Canada, together with geographical and biographical sketches
Identifier: cu31924000537757 (find matches)
Year: 1900 (1900s)
Authors: Bailey, L. H. (Liberty Hyde), 1858-1954; Miller, Wilhelm, b. 1869
Subjects: Gardening
Publisher: New York, Macmillan
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN

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ether a Hild bo hints by ;is also â weight Kinds of above an varicjiratinn. Sanscvieria d Caladium below. plant, and causing the known as variegation. Investigations conducted by the â writer on the so-called mosaic dis- ease of tobacco, which is a form of variegation, and also on many other forms of ordinary variega- tion, show quite conclusively that the disease is not caused by micro- organisms, but is due to a de- ranged condition of the nutrition of the cells. Without going into the details of tbe matter, it may l)e said that the condition is charac- terized physiologically by a marked increase in the oxidation processes in tilt:' cells, caused I»y the j")resence of an almormal anjount, or an ab- normal activity, of oxidizing fer- ment in the protoplasm. This fer- ment prevents the movement of food substances, especially starches and nitrogenous materials. The decrease of the latter is especially marked, and it i.s pndjably on ac- count of the lack of sufticient ni- trogenous food that the cells do not develop normally. The young growing buds and <lividing cells require highly organized albumi- noid foods. They do not make use, to any extent, during the pro- cess of growth and cell division, of the ordinary nitrates which are built up into nitrogenous foods by the mature cells. The oxidizing ferments, though normal constitu- ents of all cells, prevent, when they become excessively active, the proper nutrition of the dividing cells, and it is a curious fact that when these ferments are extracted from plant tissues and injected into the young buds of healthy tissues, they will, in the case of tobacco at least, cause the buds so treated to develop into variegated shoots. The ferment in question passes readily through the cell-walls of the plants and it thus be- comes evident how siich changes could be trans- mitted by grafting and budding, though no para- sitic organisms of any kind are connected with the matter. Another method of producing variegation of tobacco is by cutting the plant back severely during rapid growth. The new shoots have to develop with a small sup- ply of elaborated nitrogenous food, the larger part being removed in the severe cutting back. Shoots thus developed nearly always show variegation. The same thing is true of many other plants, espe- ciallythe potato, tomato, mulberry, etc. In fact, it appears that a plant is likely to show vaidegation whenever it is so treated that the growing buds or the forming buds, or the seeds, have to devtdop un- dersuch conditions that the ferment content of the cells is increased beyond the normal amount, and the reserve foods stored are in small amount. These changes must, therefore, lie considered as pathological in their nature, as the vitality and

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