. The algae. Algae. Fig. 135 Harveyella and Holmsella. A-E, stages in development of gonimoblasts after fertilization in Harveyella mirahilis. a = auxiliary cell, s = sterile filaments. F, filaments of parasite, Holmsella pachy- dermay in host. G, antheridia of Harveyella mirabilis. H, tetraspores in Holmsella pachyderma. e= tracks left after tetraspores have escaped, s = sterile cells, t — tetraspores in various stages, te = escaping tetraspores. (After Sturch.) are said to pass through the full floridean life cycle twice every year. It is clear that their much reduced morphological features
. The algae. Algae. Fig. 135 Harveyella and Holmsella. A-E, stages in development of gonimoblasts after fertilization in Harveyella mirahilis. a = auxiliary cell, s = sterile filaments. F, filaments of parasite, Holmsella pachy- dermay in host. G, antheridia of Harveyella mirabilis. H, tetraspores in Holmsella pachyderma. e= tracks left after tetraspores have escaped, s = sterile cells, t — tetraspores in various stages, te = escaping tetraspores. (After Sturch.) are said to pass through the full floridean life cycle twice every year. It is clear that their much reduced morphological features are to be associated with the parasitic habit, and have arisen as a result of the adoption of parasitism. The position of the genus has been the subject of controversy. In the past it has been placed in the Gigar- tinales, but is now more generally placed in the Cryptonemiales. GiGARTINALES Thallus construction in this order can be either of the central filament or fountain type, but it is often so modified in the adult plant that it is difficult to interpret. The support cell or an ordinary intercalary cell is set aside before fertilization to act as the auxihary cell. GiGARTiNACEAE: Gtgarttna (Gtgarton, grape stone). Fig. 136 This is a widespread genus, the species of which are often diffi- cult to determine taxonomically. The plants, several of which arise from a prostrate disc, vary greatly in habit from large, fiat, little- branched, foliose expansions (G. atropurpurea) to terete fronds that are irregularly pinnate or dichotomously branched. The female 242. 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
