190 Algae. 



iridescent glistening appearance which is characteristic of the pre- 

 sence of great quantities of Rhisosolenia. G. S. West. 



Lucas, A. H. S., The Gases present in the Floats (vesi- 

 clesj ofcertain Marine Algae. (Linn. Soc. N. S. Wales. Abstr. 

 Proc. p. III— IV. Oct. 25th 1911.) 



The author, not having been able to find any account of actual 

 analyses of the gases present in the floats of marine algae, made a 

 number of analyses of the gases found in the floats of Phyllospora 

 comosa, Hormosira banksii, and Cystophora monilifera. In all cases, 

 the gases consisted of oxygen and nitrogen only; in most cases the 

 Proportion of the oxygen was less than if air had been taken directly 

 into the floats, and in all notably less than in air dissolved in water. 

 In the floats of growing Hormosira, the proportion of oxygen was 

 about 12°/ only of the total volume of contained gases. While there 

 is no absolute evidence of the source of the gases, the author in- 

 clines to the view that they are derived from the air dissolved in 

 the sea-water, the plant using up a considerable proportion of oxy- 

 gen for its process of metabolism. Author's abstract. 



Price, S. R., A new Species of Debarya. (New Phytologist, X. 

 p. 87—89. pl. 2. 1911.) 



This alga was obtained from stagnant ponds on Sheep's 

 Green, Cambridge, and has been named Debarya cruciata. It 

 is a narrow species somewhat allied to D. desmidioides , and the 

 mature zygospores are quadrate-rectangular, each angle being fur- 

 nished with a colourless cylindrical hörn of variable length , which 

 arises by the transformation of part of the original gametangium 

 exactly as in D. desmidioides and D. Hardyi. G. S. West. 



Spratt, E. R., Some Observations on the Life-history of 

 Anabaena Cycadeae. (Ann. Bot. XXV. p. 369—380. pl. 32. 1911.) 



This species of Anabaena, which lives in intercellular Spaces in 

 the modified roots of Cycas, possesses short filaments and numerous 

 heterocysts. The cells have no definitely organized chromatophore 

 and the pigment is lodged in the peripheral cytoplasm. The central 

 body is simple in structure and only capable of direct division. 

 Cyanophycin granules were found to be very abundant, and gly- 

 cogen the chief product of assimilation. 



Suggestions are put forward as to the functions of the hetero- 

 cysts, in limiting the filaments, in the storage of reserve material, 

 and in producing asexual gonidia. 



The spores were found to have four methods of germination: 

 1) The Contents are protruded through a pore in the spore-mem- 

 brane; 2) the spore-membrane is ruptured; 3) the spore-membrane 

 becomes mucilaginous; 4) the Contents divide before escaping from 

 the spore-wall. The gonidia are formed by the rejuvenescence and 

 subsequent division of the contents of the heterocysts, and each is 

 capable of forming a new Anabaena filament. A. Cycadeae maintains 

 its existence in the soil in the form of heterocysts and spores, 

 which develop into gonidia, and the latter enter the tubercles of 

 the Cycas through the lenticels. G. S. West. 



