618 SUMMARY OF CURRENT RESEARCHES RELATING TO 



protoplastic structure of a scries of species selected from thirty fresh- 

 water genera, and appends a bibliography. 



North American Fresh-water Algae.* — C. A. Kofoid gives an ac- 

 count of the plankton of the Illinois River (1894-99), including a 

 discussion of the species of Kchizophyceae, Chlorophycese, Diatomacese, 

 and Conjugate found therein, with notes upon their respective seasonal 

 distributions, and the factors that control their production. 



Spanish Fresh-water Algae. f — F. B. Casares gives an enumeration 

 of twenty-one Conjugate, mostly Desmids, collected in the provinces of 

 Orense and Pontevedra, in Galicia. Instructions are given as to the best 

 time of year for collecting these algas, and the best methods of gathering, 

 preparing, and preserving the specimens. The average dimensions of 

 the species are stated. 



Fresh-water Algae of the West Riding.J — W. and G-. S. West give 

 an enumeration of more than 180 species and varieties of fresh -water 

 algae collected by them from time to time on Austwick Moss, in the West 

 Riding. Some of them are new to Yorkshire, and some to West York- 

 shire. The nature of the ground is indicated, and a list of the more 

 important vascular plants associated with the algas is added. 



Genus Haematococcus.§— W. Wollenweber publishes some inves- 

 tigations concerning Hc&matococcus. He sums up the most important 

 results as follows : — 1. H(cmatococcus can by appropriate cultivation be 

 made to pass through its complete life-history, yielding zoospores, aga- 

 metes, gametes, zygotes, aplanospores, and palmelloid states. 2. The cell- 

 membrane does not consist of cellulose. 3. The chromatophore consists 

 of a delicate green tubular scaffold, but in surface-view looks like a net. 

 4. Hmnatococcus possesses numerous (up to sixty) contractile vacuoles, 

 imbedded in the uppermost sheath of the chromatophore, and pulsat- 

 ing independently of one another. 5. These contractile vacuoles afford 

 the most trustworthy distinguishing character between Hcemotococcus 

 and Chlamydomonas. 6. Size, thickness, and shape of the zoospore- 

 membrane, development of the chromatophore, number and development 

 of the pyrenoid and of the protoplasmic pseudopodia. 7. Hmmatococcus 

 is suited to a myxo- and auto-trophic mode of life. In the latter mode 

 of life agamogony preponderates. In H. phwialis only agamogony 

 occurs. S. Stephanosphcera and Hcematococcus are referred by Schmidle 

 to Chlamydomonadeas as a subfamily (Sphaerellaceas), on account of the 

 similar morphological and physiological conditions. 9. The Red Snow 

 alga finds no place in Hcematococcus as now understood, and is to be re- 

 garded as a Chlamydomonas (C. nivalis), as Wille has shown. 



Development of Hydrodictyon.|| — R. A. Harper discusses the organisa- 

 tion of certain ccenobic plants, describing in detail the formation of the 



* Bull. Illinois State Lab. Nat. Hist., viii. (1908) pp. 19-61. 

 t Boletin R. Soc. Espanola Nat. Hist., viii. (190S) pp. 231-8. 

 % Naturalist, No. Gil (1908) pp. 101-3. 



§ Ber. Deutsch. Bot Gesell., xxvi. (1908) pp. 238-9S (5 pis., figs.). 

 || Bot. Soc. of America, publication 36 (1908) 56 pp., 1 pis. See also Bull. 

 Univ. Wisconsin Sci., iii. pp. 279-334. 



