. A handbook of cryptogamic botany. Cryptogams. 25& ALG.±: Literature. Reinke—Nova Acta Acad. , 1878. Thuret & Bornet—Etudes Phycologiques, 1S78. Hauck—(Padina) Hedwigia, 1887, p. 41. The position of the small family of Syngenetic^e, as constituted by Rostafinski, is one of great uncertainty. The two genera of which it is composed have generally been regarded as of a very low type of structure, and it is very doubtful whether they are nearly related to one another. The pro- bability seems to be in favour of both genera having been derived from the Phseosporeae by retrogress
. A handbook of cryptogamic botany. Cryptogams. 25& ALG.±: Literature. Reinke—Nova Acta Acad. , 1878. Thuret & Bornet—Etudes Phycologiques, 1S78. Hauck—(Padina) Hedwigia, 1887, p. 41. The position of the small family of Syngenetic^e, as constituted by Rostafinski, is one of great uncertainty. The two genera of which it is composed have generally been regarded as of a very low type of structure, and it is very doubtful whether they are nearly related to one another. The pro- bability seems to be in favour of both genera having been derived from the Phseosporeae by retrogressive metamor- phosis in different directions. Heckel and Chareyre (Journal de Microgra- phie, 1885) regard Hydrurus and Chro- mophyton as presenting a connecting link between the Diatomacese and the Phaeosporeas. Hydrurus Ag. consists of a fila- mentous thallus, attaining sometimes a foot in length, slimy and affixed to a conical disc, and growing in cold fresh running water. The filaments are simple below but branched above, often with exceedingly fine penicillate divisions, filled with a brown or olive endochrome identical with phycophsein. The sur- face is naked or densely covered with delicate hair-like appendages, which are occasionally fasciculate. The thallus is composed of cells dispersed through the gelatinous matrix; tow;ards the apex of the branches the cells are in close contact with one another, but in the older parts of the thallus they are some distance apart. Each is surrounded by a very delicate membrane, and Lager- heim states that some of them contain pulsating vacuoles. Propagation takes place by means of zoospores of very peculiar form, produced in the branches only, two or four from each cell. When mature the zoospores are tetrahedral, each angle being. Fig. 232.—A^ Hydntnis ienicillatns Ag. (natural size). (After Cooke.) spore (greatly magnified), heim.) B, zoo- (After Lager-. Please note that these images are extracted from scanned page images th
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