A manual of elementary zoology / by L.A. Borradaile.

  • Lancelot Alexander Borradaile
Date:
1930
Catalogue details

Licence: In copyright

Credit: A manual of elementary zoology / by L.A. Borradaile. Source: Wellcome Collection.

    107/756 page 87
    in the substance1 of the meshwork of nucleoplasm, and are revealed by staining. They consist of a kind of matter known as chromatin from the fact that by its affinity for certain dyes it is the cause of the deep staining of the nucleus.2 Besides these bodies, protoplasm often contains relatively large spaces filled with fluid known as vacuoles. Protoplasm is extremely sensitive to the action of ex- ternal agents, from which it is carefully screened Protoplasm! in the bodies of most animals. Distilled water, solutions of salts, acids, alkalies, and narcotics all have characteristic effects upon it, stimulating, inhibiting, or killing it according to their nature and strength. It is also easily stimulated by electric shocks. Changes of temperature have marked effects upon it. Moder- ate heat acts as a stimulus, causing increased activity of movements, etc. ; cold has a depressing effect. Heating above about 450 C. kills the protoplasm by causing its pro- teids to set into a solid mass or “ coagulate.” Cold below o° C. stops all exhibition of life, but unless it is extreme does not rid. Fig. 46.—A diagram of transverse section through prevent the reappearance of the ileum of the frog. c.m., Circular muscle layer; c.t., connective tissue; ep., epithelium which lines the gut; l.m., longi- tudinal muscle layer; msnt., mesentery ; per., peritoneum ; rid., longitudinal ridges of ileum. vital processes if the tempera- ture be raised. Protoplasm is, as we have said, the living part of the body. It is here that metabolism goes on and all the characteristic processes of life take place. The reception of stimuli conduction, contraction, secretion, reproduction, and so 1 Known as linin. ~ Chromatin consists of various compounds of the class known as nucleins, which contain protein united with another highly complex substance known as nucleic acid, very rich in phosphorus and often in iron. Its acidity causes it to unite with basic dyes.
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