. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . Fig. 37. Lateral view of Amphidinium sulcatum Kofoiil. ami/., amyloid body; chr., chromato-pliore; ep., anterior part of cell in front of transverse furrow; , flagellar pore; /./.,longitudinal furrow; «., nucleus; , transverse furrow (with flagellum); vac., 740 (after Kofoid). structures occur in certain species of Gymnodinium and Spirodinium, some-times forming a more or less continuous peripheral zone. Some specieso
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . Fig. 37. Lateral view of Amphidinium sulcatum Kofoiil. ami/., amyloid body; chr., chromato-pliore; ep., anterior part of cell in front of transverse furrow; , flagellar pore; /./.,longitudinal furrow; «., nucleus; , transverse furrow (with flagellum); vac., 740 (after Kofoid). structures occur in certain species of Gymnodinium and Spirodinium, some-times forming a more or less continuous peripheral zone. Some speciesof these genera throw out numerous threads of mucus, either just previous toentering the resting state or on the advent of unfavourable external con-ditions : these threads rapidly swell up and form a colourless gelatinousenvelope. The chromatophores are disc-shaped, rod-like, or band-like, and aremostly of a golden-brown colour, although Gymnodinium viride is green,G. teruginosum is blue-green, and G. cceruleum blue. The two latter organismscontain phycocyanin in addition to the green and brown pigments. The. B Fig. 38. A, longitudinal division of Gyniito-diniiun viride Penard, the fission almost com-pleted ; B, transverse fission of G. rufescens?Penard) Lemm. showing the dividing nucleus(after Penard). Only the longitudinal flagellaare shown, x about 450. Gymnodiniaceae 53 nutrition of the coloured forms is normally holophytic, but in certain casesthere appears to be in addition atruly animal-like method of takingup solid food by means of pseudo-podia protruded from the region ofthe transverse furrow. This occurs,according to Zacharias, in Gymno-dinium Zachariasi Lemm. Someforms, such as Gymnodinium fucorum,G. spirale, etc., are without chro-matophores and lead a saprophyticexistence. A few parasitic formshave also been described, notablyGymnodinium parasiticum Dogiel,G. Pouchetii Lemm., and G. roseumDogiel. The first-named lives duringpart of its life-history within th
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