ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 461 



The first are much-branched outgrowths from the basal cell, from 

 which they are not cut olf by any cell-wall. They become closely 

 adherent to the substratum and do not penetrate in any way. They are 

 poor in chlorophyll and very thick-walled. 



The second kind of holdfasts arise sideways from a plant, at the 

 base of a cell, not, as in the case of an ordinary branch, from its upper 

 end. A thin branch cell grows out hearing at its end the holdfasts 

 which are much branched and poor in chlorophyll. 



The third kind is formed on the ends of thin, many-celled branches ; 

 and they have the appearance of helicoid tendrils. These are rare. 



Although no description of these holdfasts is given for C. cornea, 

 the author places his ball-like plant temporarily under that species until 

 such time as he can further examine material of his plant and settle on 

 its position in the genus. The manner of ball-formation is the same 

 in C. cornea as in C. Sauteri, but the centre of the former is solid, while 

 the centre of C. Sauteri is hollow. 



Variation in Fragilaria crotonensis.* — C. Schroter and P. Vogler 

 give statistics as to the variation of this diatom, dredged in the Lake of 

 Zurich at the rate of once or twice a month continuously from 1896— 

 1901. They describe the methods of examination and give tables of 

 their results. Four distinct forms of the species are recognised and 

 described. Their occurrence in the lake is variable. 



Fresh-water Algse of Switzerland.! — P. Chodat publishes a con- 

 siderable contribution to our knowledge of fresh-water algse and of the 

 cryptogamic flora of Switzerland. It is mainlv the result of much 

 personal experience and study of the polymorphism of this group of 

 plants. The book is divided into four parts: — (A) Collection and pre- 

 servation of fresh-water algae. (B) Morphology, in which the author 

 treats under separate headings of: — Protoplasm, Vacuoles, Flagella, 

 Stigma, Cbromatophores, Pyrenoid, Nucleus, Membrane, Pluricellular 

 thallus, Hairs and bristles, Rhizoids and organs of attachment, Organs 

 of multiplication. (C) Biology, under the headings of Light, Tempera- 

 ture, Nutrition, Tropism, Classification according to biology, Parasitism, 

 Symbiosis, Holophytes, Aquatic limnophils, Plankton, Cryoplankton, 

 Dispersal. (D) Classification. This last part occupies 264 pages of 

 the book and deals with the Pleurococcoidese, including the Schizo- 

 gonioideae, and with the Chroolepoideae. The families Palmellacese, 

 Volvocineae, Protococcoidea?, and Pleurococcaceae are treated with the 

 completeness of monographs, and throughout the classificatory part of 

 the book the descriptions, the very full notes, and the keys are of great 

 value. 



Marine Algae of Iceland.} — Helgi Jonsson publishes a list of the 

 marine algse of Iceland, founded on collections made by himself and 

 others, and preserved for the most part in the Copenhagen Museum. 

 Seventy-one species are recorded with certainty, of which Ghantransia 

 Alarise and Rhodocorton repens are new species. Both are figured and 



* Vierteljahrschr. Naturforsch. Ges. Zurich, xlvi. (1902) pp. 185-206 (5 figs.). 

 t Alguee vertes de la Suisse. Pleurococco'ides-Chroolepoides. Beitrage z. krypt. 

 Fl. Schweiz, i. (1902) pp. 373 (264 figs.). 



X Botan. Tidsskrifr, xxiv. (1901) pp. 127-55. 



