. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. 24 BACTERIA AND SOIL FERTILITY cocci (singular, coccus). Often when two remain connected to- gether we have a coffee bean-shaped organism or sometimes an organism similar to the head of a lance. The cocci may be large or small and group themselves in various ways. The third group of bacteria are the spirilla (singular, spiril- lum), and may be likened to a corkscrew. The spiral may be loosely or tightly coiled. There may be one,^ two, or more coils. At times the organism may be so small and the curve so sl
. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. 24 BACTERIA AND SOIL FERTILITY cocci (singular, coccus). Often when two remain connected to- gether we have a coffee bean-shaped organism or sometimes an organism similar to the head of a lance. The cocci may be large or small and group themselves in various ways. The third group of bacteria are the spirilla (singular, spiril- lum), and may be likened to a corkscrew. The spiral may be loosely or tightly coiled. There may be one,^ two, or more coils. At times the organism may be so small and the curve so slight that the organism viewed under the microscope appears to be "; Roughly speaking, there are about three times as many bacilli known as cocci and iive times as many cocci as spirilla. Variation in Form.—If one plants the Irish potato he expects to harvest Irish potatoes and not sweet potatoes. So it is with bacteria. If one plants bacilli, the bacilli and not the cocci will grow, or in other words the mi- croscopic plants breed true just as do the higher plants. One may plant a potato and harvest potatoes which vary considerably in size and shape. The same is true in regard to bacteria. There may be a great variation within the same group. Some bacilli may reproduce club-shaped organisms many times larger than the average. This is characteristic of the organism which causes diphtheria, whereas the organisms which grow in the nodules on the roots of alfalfa often take on the form of stars, crosses, and various grotesque shapes. These so-called involution forms of bacteria have been likened to the lame and halt in human society. However, this is hardly an apt illustration, for these peculiar shaped organisms possess all the powers of the normal bacteria, and if they find their way into the body of a plant or animal they. Fig. 5.—Large bacilli (after Harrison).. Please note that these images are extracted from scanned page images that may have been di
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbacteriologyagricult
