. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . clusions have not been verified, even for 286 Ulotrichales U. zonata, and they do not apply to several of the smaller species of Ulothrixl. Four ofKlebs main conclusions were: (1) that if, after cessation of zoospore-formation, thefilaments were transferred from nutritive solutions to water, then zoospore-formationrecommences ; (2) that zoospores were formed by transferring filaments from a nutritivesolution to water and then putting the cult
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . clusions have not been verified, even for 286 Ulotrichales U. zonata, and they do not apply to several of the smaller species of Ulothrixl. Four ofKlebs main conclusions were: (1) that if, after cessation of zoospore-formation, thefilaments were transferred from nutritive solutions to water, then zoospore-formationrecommences ; (2) that zoospores were formed by transferring filaments from a nutritivesolution to water and then putting the cultures in the dark for three days ; (3) thattransference of the filaments from running water to quiet water, or bringing from anatural habitat into a room, resulted in zoospore-formation, the cause being attributedto the diminution of the amount of air in the water ; (4) that observations wereagainst a rise in temperature being a special cause in inducing the formation ofzoospores. Klebs first statement does not apply to the smaller species of Ulothrix and repeatedexperiment has failed to confirm it in U. zonata. Experiments extending over two years. Fig. 183. A, part of filament of Ulothrix sequalis Kiitz. to show single chloroplast with pyreuoid(py). B and C, U. zonata (Web. & Mohr) Kiitz. B, part of filament showing germinationof microgonidia (which have never been motile) to form new plants ; C, similar germinationof macrogonidia. D, Stichococcus variabilis W. & G. S. West. E, aquatic form ofS. flaccidus (Kiitz.) Gay, only in outline except for one cell which shows partial frag-mentation of chloroplast. F, S. bacillaris Nag. All x 500. do not bear out his second statement in the case of either U. tenuissima or U. his third statement this was not found to be true in the case of U. zonataand U. subtilis unless the transference was accompanied by a decided change in tem-perature. In contrast to his fourth statement experiments conducted over a long peri
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