. Experimental morphology. Protoplasm; Growth. 34 CHEMICAL AGENTS AND PROTOPLASM [Ch. I Returning now to the simple organisms, let us consider the kinds of chemical substances which incite to a response. Oxygen is for almost all organisms a means of attraction. Various methods of demonstrating this have been used. Thus Stangb ('90, p. 139) filled capillary tubes with pure oxygen, under an air-pump, and brought them to the water containing zoospores, which then penetrated into them. The aggregation of zoospores and bacteria to the edges of the cover-glass, to the open end of a capiUary tube (Ad
. Experimental morphology. Protoplasm; Growth. 34 CHEMICAL AGENTS AND PROTOPLASM [Ch. I Returning now to the simple organisms, let us consider the kinds of chemical substances which incite to a response. Oxygen is for almost all organisms a means of attraction. Various methods of demonstrating this have been used. Thus Stangb ('90, p. 139) filled capillary tubes with pure oxygen, under an air-pump, and brought them to the water containing zoospores, which then penetrated into them. The aggregation of zoospores and bacteria to the edges of the cover-glass, to the open end of a capiUary tube (Adekhold, Air bubble â¢f; "^*-. Zone of 'â ^ Zone of AnopJirys . ''v :i-:r-. ct. â¢=""=-^'^'* J b. Fig. 2. â a. Corner of the glass slip covering a drop of liquid containing Spirillum and Anophrys, showing their aggregation with reference to the aerated bound- ing film of the drop. 6. An air-buhble in the drop, showing aggregation of the organisms about it. (From Massakt, '91.) '88, p. 314), or to an enclosed air-bubble, are well-known phe- nomena. (Cf. Massabt, '91, p. 159; Vbewoen, '89, p. 107 ; and see Fig. 2.) Estgelmann ('94) has employed a still more refined method of studying attraction towards oxygen. A drop of foul water is put on a glass slide with an alga cell in the centre, and is covered by a cover-glass whose edges are hermetically sealed by vaseline. The bacteria are uniformly distributed in the water, moving in a lively manner, since they gain oxygen everywhere. If the slide thus prepared is kept in the dark, the oxygen is gradually consumed and the bacteria become quiescent, showing no distribution with reference to the cen- tral chlorophyllaceous body (Fig. 3). If the slide is now exposed to the light, oxygen is produced by the alga and a regular distribution of the bacteria in two distinct regions â in a mass around the central alga, and in a. Please note that these images are extracted from scanned page images that may have been digitally
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