The essentials of histology : descriptive and practical for the use of students / by E.A. Schäfer.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: The essentials of histology : descriptive and practical for the use of students / by E.A. Schäfer. Source: Wellcome Collection.

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    during life to exhibit movements which are apparently spontaneous, and when the cell is uninclosed by a membrane a change in the shape, or even in the position of the cell, may be thereby pro¬ duced. This is characteristically shown in the movements of the unicellular organism known as the amoeba (fig. 2); hence the name amoeboid movement, by which it is generally designated.1 The proto¬ plasm often exhibits a granular appearance. This is sometimes due to the fact that it contains a very fine reticulum or spongework, which appears under high powers of the microscope in the form of a network (fig. 1), the remainder of the protoplasm being a clear soft substance which occupies the interstices of the reticulum, and may also cover the Fig. 2.—Successive changes exhibited by an amoeba. 4 8 (Verworn.) surface or project beyond the rest of the cell. The granular appear¬ ance above mentioned is often caused by the knots in the network appearing when imperfectly observed as separate granules. The material which forms the reticulum is termed sponc/ioplasm; the clearer a cell often, if not always, includes actual granules of a proteid nature; but it is uncertain whether such granules are essential con¬ stituents of the protoplasm (as contended by Altmann) or materials which have been formed by the protoplasm, and which are in a sense accidental inclusions. That they are of great importance appears to be evident from the fact that many of the chemical changes of cells 1 The amoeboid phenomena of cells will be studied later (in the colourless blood- corpuscles) (Lesson V.).