Structural and chemical properties of the plasmalemma of Amoeba proteus

• 1.1. The structural and chemical properties of the plasmalemma of Amoeba proteus were investigated with optical, electron optical and histochemical methods. Normal and centrifuged amoebae were used as well as specimens fixed with different fixing fluids.
• 2.2. The double refraction of plasmalemma is positive in relation to the tangent. Imbibition with liquids of different refractive index brings about considerable changes in double refraction. It is concluded from the curve of refraction values that the plasmalemma shows birefringence which is for the most part “textural” (Formdoppelbrechung).
• 3.3. In electron optical preparations the external surface of the plasmalemma appears to persist even after treatment with very different fixing fluids, as a sintered globular film, formed by densely packed minute globular bodies. The thickness of the film is about 500 Å.
• 4.4. The following histochemical tests suggest the conclusion that the plasmalemma contains a great amount of mucopolysaccharides, probably coupled to proteins: strong metachromatic colorability by some basic dyes; presence of carbohydrates as shown by a positive Hotchkiss reaction; the specific action of hyaluronidase upon the plasmalemma of fixed amoebae; the solubility in water at raised temperatures; the rapid postmortal lysis.
• 5.5. The experimental data obtained might be explained by the following assumption. The plasmalemma is a mucous surface coat composed predominantly of globular bodies (probably mucoproteids). The diameter of the single body is considerably less than the wave length of light; therefore the whole complex of these minute bodies gives textural birefringence. The adhering layers of hyaloplasm may act, together with the surface coat as a “mixed body” (Mischkörper) and influence birefringence according to the various precipitating action of fixing fluids.