. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . [Inoderma Kiitzing is very doubtful.] It has been asserted by various recent authors (Gerneck, 07 ; Wille 09 ; etc.) thatNagelis genus Glceocystis merely includes developmental stages of members of the Chlamy-domonadese and Ulotrichales, and should therefore be deleted. This is very likely true ofa number of the so-called species which were at one time described, but there is as yet noproof that this is so in other cases. In Glceocystis gigas
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . [Inoderma Kiitzing is very doubtful.] It has been asserted by various recent authors (Gerneck, 07 ; Wille 09 ; etc.) thatNagelis genus Glceocystis merely includes developmental stages of members of the Chlamy-domonadese and Ulotrichales, and should therefore be deleted. This is very likely true ofa number of the so-called species which were at one time described, but there is as yet noproof that this is so in other cases. In Glceocystis gigas, for example, the colonies appeart be quite distinctive, and four daughter-cells arranged from the first as a tetrad areusually formed in each mother-cell. Much further investigation is required on some ofthese Alga;. Family Dictyosphseriacese. This family is closely allied to the Palmellacea?, but is easily distinguishedby the fact that portions of the old mother-cell-walls remain as thong-likeattachments to the cells and cell-groups. This character is best seen inDictyosphssrium, in which the persistent portion of the mother-cell-wall. Fig. 116. Dictyosphserium pulcliellnm Wood. 1, old colony; 2, single cell dividing; 3 and 4,two views of group of four cells, g, mucilaginous envelope ; zw, cruciform remnants ofold cell-wall connecting the daughter-cells. (After Senn, from Oltmanns.) x about 1000. may become either a bifurcate or quadrifurcate thong (fig. 116) playing aconsiderable part in maintaining the definite globose or ellipsoid form ofthe colonies, which are in addition enveloped in a copious mucilage. InRadiococcus the relics of the mother-cell-walls are less important as binding-strands, possibly on account of the fact that the colonies are attached byone side of the large mucous envelope to the leaves of aquatic macrophytes,whereas those of Dietyosphferium are free-floating. In Westella and Protococcaceae 191 Dimorphococcus (fig. 117) there is comparatively li
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