. General physiology; an outline of the science of life. LIVING SUBSTANCE 85 I. The Gmond-substance of Protoplasm As already noted, the ground-substance of protoplasm, in which the granules, etc., are embedded, appears upon superficial examina- tion completeh- homogeneous. This can be seen best in cells that contain onl}- a few solid constituents stored in their ground- substance ; it is especially evident in many Amaibm, which are free-living cells possessing naked protoplasmic bodies that creep about at the bottom of stagnant water, constantly changing their form, and represent the lowest an
. General physiology; an outline of the science of life. LIVING SUBSTANCE 85 I. The Gmond-substance of Protoplasm As already noted, the ground-substance of protoplasm, in which the granules, etc., are embedded, appears upon superficial examina- tion completeh- homogeneous. This can be seen best in cells that contain onl}- a few solid constituents stored in their ground- substance ; it is especially evident in many Amaibm, which are free-living cells possessing naked protoplasmic bodies that creep about at the bottom of stagnant water, constantly changing their form, and represent the lowest and simplest organisms inhabiting the surface of the earth. These interesting elementary organisms usually form upon their surface pseudopodia which are wholly free from granules, broad, finger-shaped, or lobate, and appear com- pletely hyaline and structureless (Fig. 16, p. 75, and Fig. 28). In fact, in the Amcehm the hyaline protoplasm not rarely is completely structureless. All investigations up to the present time which have been undertaken with the best microscopic methods agree in this. But this actual homogeneity of the ground- substance of protoplasm is not the rule; on the contrary, the employment of high magni- fying powers shows that by far the majority of cells possess in reality in their apparently homogeneous ground-mass an extremely fine and characteristic structure. Remak ('44) observed that not only nerve- fibres but also the ganglion-cells of the central nervous system possess a very fine fibrous or fibrillar structure—an observation that was confirmed and extended by a large number of investigators, especially by Max Schultze (71). A striated structure was later found in the protoplasm of various other cells, gland-cells, epithelium-cells, muscle-cells, etc., and thus the idea was formed by various investigators that a fibrillar struc- ture is wide-spread in protoplasm; this view is still defended to- day, especially by Flemming, Ballowitz, and Camillo Schnei
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