Human physiology : prepared with special reference to students of medicine / by Joseph Howard Raymond.

  • Raymond, Joseph H. (Joseph Howard), 1845-1915
Date:
1901
Catalogue details

Licence: Public Domain Mark

Credit: Human physiology : prepared with special reference to students of medicine / by Joseph Howard Raymond. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    and attraction-sphere have l>een found in so many cells that they mav be regarded as essential constituents of every cell. Protoplasm.—This is the principal ])art of a cell, and is of an albuminous nature. Chemically it consists of water (75 per cent, or more), proteids, lecithin, cholesterin, and phosphates and chlo- rids of .sodium, potassium, and calcium, and sometimes fat and glvcogen. Microscopically examined it is found to be made up of spongioplasni and hyaloplasm. Spoiif/ioplasiii.—Under high powers of the microscope the pro- toplasm of a cell presents the appearance of a fine network, called reticulum, sponrjeicork, or spongioplasm. This network has in it knots, which give to it a granular appearance. These knots or granules are of the same chemic nature as the network—that i.s, are albuminous or proteid. It is still undecided whether these granules are constituent parts of the protoplasm or are its products. Collectively they are denominated granulopla-im. Other granules mav be present which are not connected with the network, and which are not proteid in character, but fatty or starchy or con- tain coloring-matter. In some instances they are of an inor- ganic natin-e. Granules of this latter kind constitute paraplasm ; by which is meant any and all material contained in a cell, not being an actual part of it, whether there as pabulum or food for the cell, or as waste material to be excreted. Hyaloplasm,—In the meshes of the spongioplasm is the hyalo- plasm, a clear substance differing but slightly in its consistence from the spongio])lasm, although it is less .solid. Ameboid Movement.—Protoplasm is endowed with the power of motion, which from its resemblance to the motion of the anieba, a minute animal, which is but a mass of protoplasm, is called ameboid. Examined under the microscope the ameba puts out from its sides projections of its protoplasm—pseudopodia; and later the whole mass flows into one or more of these projections, thus changing its position and its shape. This ameboid movement takes place in the white l)lood-corpuscle, and in some other cells as well as in the ameba. The pseudopodia are frequently drawn hack into the protoplasm, or retract, thus illustrating the posses- sion by the protoplasm of contractility. Their formation is due to an outflowing of the hyaloplasm, and their retraction to return of the hyaloplasm to the interstices of the reticulum. Ameboid movement is said to be spontaneous; but if so, it can also be pro- duced by the action of heat, by dilute solutions of salt, by mod- erate currents of electricity, and by many other agents, all of ■which are called stimuli, because of their power to stimulate this movement. On the other hand, certain agents have the power of stopping or inhil)iting the movement if it has begun. Thus a temperature above 40'^ C. or below 0° C. acts as an inhibitant, Avhile if the high temperature is continued the protoplasm is coag-