Myxophycece 311 



The observations of both Hegler and Kohl seem to show that 

 glycogen (or a substance much resembling it) is the first product 

 of carbon-assimilation. Chodat has pointed out that mucilage, 

 soluble starches and cyanophycin may make their appearance in 

 all parts of the cytoplasm. Cyanophycin is a reserve albuminous 

 substance containing both nitrogen and phosphorus, and it occurs 

 in small granules which swell up rapidly on the addition of hydro- 

 chloric acid. These granules occur abundantly in the spores of the 

 Myxophycese and are used up during their germination. 



Minute oil-drops may also occur in the cytoplasm. 



Etard and Bouilhac 1 state that Nostoc punctiforme can maintain 

 itself by a saprophytic existence in absolute darkness, as it has the 

 power of assimilating organic substances such as glucose. 



Certain of the free-floating Myxophyceae of the genera 

 Glceotrichia, Anabcena, Ccelosphcerium, etc., which sometimes occur 

 abundantly in the plankton, contain dark red granules scattered 

 through the cytoplasm. Klebahn 2 and others have asserted that 

 these red granules are gas vacuoles directly concerned with the 

 floating capacity of the Alg33 which possess them. This assertion, 

 however, is by no means proven, Brandt 3 having found them in 

 species which do not float ; and there is evidence to show that in 

 some cases they are most probably of an oily nature. Should they 

 ultimately prove to be gas vacuoles, then the cytoplasm of certain 

 of the blue-green Algae contains both gas and liquid (cell-sap) 

 vacuoles. 



In some of the Myxophycese, and possibly in many others, there 

 is a protoplasmic continuity between the cells of the filaments. 

 Wille 4 was the first to point this out in Stigonema compactum var. 

 brasiliense. Borzi 5 described these protoplasmic connections in 

 species of Nostoc and Anabcena, and Nadson has figured them in 

 Aphanizomenon and Tolypothrix. It is in certain species of 

 Stigonema that these protoplasmic connections are most con- 

 spicuous, these plants presenting a condition precisely analogous 

 to the protoplasmic continuity of the cells of the Rhodophyceas. 

 In all cases the continuity appears to be effected by a median pore 



1 Etard & Bouilhac in Comptes Rendus, cxxvii, 1898, p. 119. 

 - Klebahn in Flora, 1895, Ixxx ; in Bot. Zeitung, 1897, Iv. 

 s Brandt in Berichte Deutsch. Bot. Ges. 1901, xix. 



4 Wille, 'Bidrag til Sydamerik. Algfl.,' Bib. till K. Sv. Vet.-Akad. Handl. 1884. 

 no. 18, p. 6, t. 1, f. 20. 



5 Borzi, 'Le comun. intracell. della Nostocb.,' Malpighia, i, 1887. 



