Kirkes' Handbook of physiology / revised and rewritten by Charles Wilson Greene.

  • Kirkes, William Senhouse, 1823-1864.
Date:
1910
Catalogue details

Licence: Public Domain Mark

Credit: Kirkes' Handbook of physiology / revised and rewritten by Charles Wilson Greene. 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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    vegetable circulation, whereas the movement of the protoplasm round the interior of the cell is called rotation. The first account of the movement of protoplasm was given by Rosel in 1755, as occurring in a small Proteus, probably a large fresh-water ameba. His description was followed twenty years later by Corti's demonstration of the rotation of the cell sap in characeas, and in the earlier part of the last century by Meyer in Vallisneria, 1827; Robert Brown, 1831, in Staminal Hairs of Tradescantia. Then came Dujardin's description of the granular streaming in the pseudopodia of Rhizopods and movements in other cells of animal protoplasm (Planarian eggs, von Siebold, 1841; colorless blood corpuscles, Wharton Jones, 1846). The Power of Response to Stimuli, or Irritability.—Although the move- ments of the ameba have been described above as spontaneous, yet they may be increased under the action of external agencies which excite them and are therefore called stimuli. If the movement has ceased for the time, as is the case if the temperature is lowered beyond a certain point, move- ment may be set up again by raising the temperature. Contact with foreign Fig. 5.—Cell of Tradescantia Drawn at Successive Intervals of Two Minutes.—The cell contents consist of a central mass connected by many irregular processes to a peripheral film, the whole forming a vacuolated mass of protoplasm, which is continually changing its shape. (Schofield.) bodies, gentle pressure, certain salts, and electricity produce or increase the movement in the ameba. The protoplasm is, therefore, sensitive or irritable to stimuli, and shows its irritability by movement or contraction of its mass. The effects of some of these stimuli may be thus further detailed: a. Changes of Temperature.—Moderate heat acts as a stimulant; the movement stops below 0° C. (32° F.), and above 40° C. (104° F.); between these two points the movements increase in activity; the optimum tempera- ture is about 37° to 38° C. Exposure to a temperature even below 0° C. stops the movement of protoplasm, but does not prevent its reappearance if the temperature is raised; on the other hand, prolonged exposure to a tem- perature of over 40° C. kills the protoplasm and causes it to enter into a condition of coagulation or heat rigor. h. Mechanical Stimuli.—When gently squeezed between a cover and