Elements of biology, with special Elements of biology, with special reference to their rôle in the lives of animals elementsofbiolog00buch Year: 1933 BACILLI air-contammg oxygen are common. These are called anaerobes. Some types are killed by atmospheric oxygen; they are obliged to live shielded from the air. These are the OBLIGATORY ANAEROBES. Othcrs peri- odically live in the absence of oxy- gen; these are facultative ana- erobes. Bacteria. We return now to the parasitization of animals by micro- scopic forms. The most important of these are plant parasites which be- long to the Schizophyta
Elements of biology, with special Elements of biology, with special reference to their rôle in the lives of animals elementsofbiolog00buch Year: 1933 BACILLI air-contammg oxygen are common. These are called anaerobes. Some types are killed by atmospheric oxygen; they are obliged to live shielded from the air. These are the OBLIGATORY ANAEROBES. Othcrs peri- odically live in the absence of oxy- gen; these are facultative ana- erobes. Bacteria. We return now to the parasitization of animals by micro- scopic forms. The most important of these are plant parasites which be- long to the Schizophyta, the fission plants. These are the bacteria (p. 77). Not all bacteria are parasitic on Man, nor do all those which do parasitize Man cause disease. Bac- teria are small single-cell plants, so small that none of them can be distinguished by the unaided eye and so small that some of them are beyond the powers of the microscope. A single definite nucleus is not distinguishable; what is taken to be nuclear material in some forms is scattered through- out the cell. They reproduce rapidly under suitable conditions. There are very many varieties known and perhaps many others unknown; they parasitize all sorts of animals and plants, feed on SPIRILLI Fig. 26.—Various forms of bacteria. (From several au- thors.)
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