. Botany for agricultural students. Plants. BACTERIA 341 of the organism, develop abnormally, producing scabby formations which constitute the scabby areas on the tuber or root. The Plasmodia are finally transformed into spores which are liberated as powdery masses as the infected tissues die and the spore masses break open. It has been found that the spores can live in the ground for a num- ber of years and may also live adhering to the rind of the Potato. Treating seed Potatoes with weak solu- tions of formaldehyde or corrosive sublimate to kill the spores adhering to the tubers, and rotatin
. Botany for agricultural students. Plants. BACTERIA 341 of the organism, develop abnormally, producing scabby formations which constitute the scabby areas on the tuber or root. The Plasmodia are finally transformed into spores which are liberated as powdery masses as the infected tissues die and the spore masses break open. It has been found that the spores can live in the ground for a num- ber of years and may also live adhering to the rind of the Potato. Treating seed Potatoes with weak solu- tions of formaldehyde or corrosive sublimate to kill the spores adhering to the tubers, and rotating crops, so that the Potatoes are not planted in infected soil are means of controlling the Fig. 294. —An lush Potato attacked by disease. a Myxomycete, Spongospora svbterranea. Bacteria. Bacteria, of which there are 1400 or more species, are the smallest of plants, and their study requires microscopes of a very high power of magnification. Some spherical forms, visible only through the best microscopes, are less than of a millimeter in diameter, and some Bacteria are known to exist that are ultramicroscopic, that is, too small to be seen with the best microscopes. They are present almost everywhere, occurring in the soil, in water, in the air, and in all organic bodies living or dead. Although so insignificant in size, they are of great im- portance, because the service of some forms is indispensable to our welfare, while the forms which cause diseases are destructive to both plants and animals. The disease-producing forms are commonly known as germs or microbes. So numerous and important are these simple plants that their study now forms a special subject called Bacteriologj/. The plant body of the Bacteria consists of a single cell. Bac- teria are of three general forms: coccus forms, which are globular; bacillus forms, in which the shape is rod-like; and spirillum forms, in which the plant body is a curved rod (Fig. 295).. Please note that these images are extracte
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1919
