. The algae. Algae. ^i- plethysmothallus 2X f B prothallus X plantule 2x. Fig. 93 Diagram of life cycles of Dictyosiphon foeniculaceus (A) and Asperococcus bullosus (B) enables the development of the macroscopic phase to take place once more. There is no evidence of either meiosis or of gametic fusion. In it would appear that the life cycle is depend- ent upon the behaviour of the zooids from the unilocular sporangia where meiosis has been shown to take place. If they fuse, the zygote develops first into a 'streblonema' phase, so-called from the brown alga it resembles, and then i
. The algae. Algae. ^i- plethysmothallus 2X f B prothallus X plantule 2x. Fig. 93 Diagram of life cycles of Dictyosiphon foeniculaceus (A) and Asperococcus bullosus (B) enables the development of the macroscopic phase to take place once more. There is no evidence of either meiosis or of gametic fusion. In it would appear that the life cycle is depend- ent upon the behaviour of the zooids from the unilocular sporangia where meiosis has been shown to take place. If they fuse, the zygote develops first into a 'streblonema' phase, so-called from the brown alga it resembles, and then into a plantule from which a new adult plant can arise. In this case there is no evidence for the exist- ence of a gametophytic generation, nor has any evidence been obtained to show that such streblonemoid plants can reproduce themselves by means of sporangia. If no fusion of the zooids from the unilocular sporangia takes place the *streblonema' phase is again produced parthenogenetically, but under these circumstances plurilocular sporangia are formed which give rise to a new ^streblo- nema' generation, nor has any investigator under such conditions succeeded in obtaining macroscopic plants again and so it has been suggested, therefore, that sex has been inhibited in these plants. i66. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Chapman, V. J. (Valentine Jackson), 1910-. London, Macmillan; New York, St. Martin's Press
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Keywords: ., bo, bookcentury1900, bookcollectionbiodiversity, booksubjectalgae
