. General physiology; an outline of the science of life. LIVING SUBSTANCE 67 original Monera is constantly diminishing, and the few that cannot yet be obtained for fresh investigation are now also regarded by most investigators as nucleated cells in which the earlier incomplete technique was not able to demonstrate nuclei, just as was the case with the others that are now recognised as nucleated. The Bacteria have defied much longer than the if owe™ attempts to find in them a differentiation corresponding to the nucleus and protoplasm of other cells. All imaginable methods of staining and the

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. General physiology; an outline of the science of life. LIVING SUBSTANCE 67 original Monera is constantly diminishing, and the few that cannot yet be obtained for fresh investigation are now also regarded by most investigators as nucleated cells in which the earlier incomplete technique was not able to demonstrate nuclei, just as was the case with the others that are now recognised as nucleated. The Bacteria have defied much longer than the if owe™ attempts to find in them a differentiation corresponding to the nucleus and protoplasm of other cells. All imaginable methods of staining and the strongest microscopic powers were not able to demon- strate the two different kinds of living substance within their minute and apparently com- pletely homogeneous bodies. This state of our knowledge continued until a very few yeava ago, in spite of the great advance that bacteriology made. Recently, however, BUtschli ('90) succeeded in discovering a fine structure in the bodies of Bacteria. He found that by the use of very strong magni- fying powers and not too strong illumination certain specific staining-reagents, which, as, e.g., hsematoxylin, colour only the nuclear substance and not the protoplasm, make visible two different substances in the bodies of Bacteria; one of these is stained intensely, the other not at all. The quantitative relations of the two substances are characteristic: the volume of the stained substance is usually greater than that of the un- stained, but the relative arrangement of the two is different in different species. In one species, as, e.g., Bacterium lineola (Fig. 9, a), the stained substance lies in the middle, and the unstained substance forms a delicate peripheral layer about it; in others, especially the corkscrew-like forms of Spirillum, such as Spirillum imclula (Fig. 9, h), which is common in stagnant water, the un- stained substance is accumulated at one end or both ends of the elongated body, and the latter consists otherwise wholly