. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Borgesen: Rhodophyceæ of the Danish W. Indies. 21. Acrochætium crassipes var. ty pica. A and B, two plants growing on Cen- troceras; B, with a hair (300 : 1). C, piece of a branch mersed with the basal part in the wall of the host plant, in agreement with M. A. Howe's description of Acrochætium catenulatum'^). The basal cell bears as a rule one or two erect filaments which most often are more or less curved and decumbent and graduallly taper towards their summits, the basal cell being the thickest of all. Hairs seldom occur; most of
. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Borgesen: Rhodophyceæ of the Danish W. Indies. 21. Acrochætium crassipes var. ty pica. A and B, two plants growing on Cen- troceras; B, with a hair (300 : 1). C, piece of a branch mersed with the basal part in the wall of the host plant, in agreement with M. A. Howe's description of Acrochætium catenulatum'^). The basal cell bears as a rule one or two erect filaments which most often are more or less curved and decumbent and graduallly taper towards their summits, the basal cell being the thickest of all. Hairs seldom occur; most of the plants are quite destitute of them. Where they with monosp'orangia (300 :1) are present they are always to be found fj'^'p^^ ZTfliS^t at the tips of the filaments (Fig. 11B). The chromatophore is stellate with a central pyrenoid. In most of the cells plenty of starch is present and the contents of the cells then have a quite homogenous appearance ; but when boiled and coloured e. g. by means of hæm- alun the stellate chromatophore is easily seen. var. longiseta nov. var. Upon specimens of Chætomorpha antennina from the harbour of St. Thomas and on Chætomorpha brachygona from Christianssted was found abundantly a small Acrochætium which shows so much likeness to Acrochætium crassipes that I have no doubt in referring it to this species from which it essentially differs by the usual presence of long hairs. The basal cell originating from the ger- minating spore is, as is the case in var. typica, the largest of the whole plant (Fig. 12), being 8—10 ^y. in diameter. It is fixed to the host plant by means of a ring of cementing sub- stance and, so far as I have been able to see, it is also often somewhat immersed in the wall of the host (Fig. 12, 13 e). From the basal cell arise a single or 2—3 suberect branches, the cells of which grow gradually thinner and at the same time longer towards. Please note that these images are extracted from scanned page images that ma
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