General physiology; an outline of the science of life . ive organismis possible only by the employment of very small autonomouselements, such as the cells. Fig. 21.—a, A smooth muscle-cell.(After Schiefferdeeker.) b. Sper-matozoon of Salamandra niacv-lata. (After Hertwig.) k, Head ;sp, tip ; m, middle-piece ; v, un-dulating membrane; ef, end-thread. 80 GENERAL PHYSIOLOGY 2. Protoplasm The mistake has frequently been made of considering protoplasm1a chemically unitary substance. This idea involves a double error,for, first, the conception of protoplasm, as created by the earlier cell-investigat
General physiology; an outline of the science of life . ive organismis possible only by the employment of very small autonomouselements, such as the cells. Fig. 21.—a, A smooth muscle-cell.(After Schiefferdeeker.) b. Sper-matozoon of Salamandra niacv-lata. (After Hertwig.) k, Head ;sp, tip ; m, middle-piece ; v, un-dulating membrane; ef, end-thread. 80 GENERAL PHYSIOLOGY 2. Protoplasm The mistake has frequently been made of considering protoplasm1a chemically unitary substance. This idea involves a double error,for, first, the conception of protoplasm, as created by the earlier cell-investigators, was not a chemical but a morphological conception,and, secondly, it applied to the whole content^ of the cell, with theexception of the nucleus. The cell-contents is, however, in neitherthe chemical nor the morphological sense a unitary substance, butis a mixture of many morphological constituents; and it mustconstantly be borne in mind that, since it is impossible to separateone or another constituent as accessory, the limitation of the term A. Fie. 22.—a, Epidermis-cells from the frog ; the living- substance appears completely hyaline bClepsid-nna blattarum, a unicellular gregarine from the intestine of a cockroach ; the protoplasmis entirely filled with granules. protoplasm to certain constituents of the cell is wholly inadmissibleand leads to evil consequences. The conception of protoplasm,therefore, should be maintained under all circumstances strictly in itsoriginal sense as a comprehensive morphological conception; proto-plasm is a sum, a mixture, of very different morphological if by degrees its individual constituents become known mor-phologically and chemically, the comprehensiveness of the termwill not thereby be set aside. Whatever significations the varioussubstances may have in the vital process of the cell is a wholly dif-ferent question, and does not affect the conception of protoplasm. LIVING SUBSTANCE 81 When the contents of protoplasm a
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Keywords: ., bookcentury1800, bookdecade1890, bookidgen, booksubjectphysiology
