484 RECORD OF SCIENCE FOR 1887 AND 1888. 



ALG^. 



The most important American work is the long-promised "Fresh- 

 water Algse of the United States," by Francis Wolle. It is comple- 

 mental to the author's " Desmids of the United States," which was pub- 

 lished in 1882, and makes two handsome volumes, one of text and one 

 of plates. The atlas contains 151 plates and over 2,300 illustrations, 

 drawn from nature by the indefatigable author himself. The classifica- 

 tion adopted is, so far as applicable, that employed for the Marine 

 Algpe, viz : Ehodophyceai, chlorophycea^, and cyanophycese, the melan- 

 ophycese not being represented. The classification, however, is unex- 

 plained and the exact views of the author are difficult to ascertain- 

 The subject of polymorphism among alg* is given a prominent place. 



Bennett (Journ.Linn. Soc, Loud., xxiv) has recently proposed some 

 modificatious in the existing systems of classification of Algae, based 

 largely on retrogression or degeneration, which, according to the au- 

 thor is manifested by more or less suppression of reproduction or vege- 

 tative organs. He traces the various forms of vegetable life to three 

 lines of descent, represented by three distinct kinds of cell-contents,, 

 viz: Colorless, blue-green, and pure green. The first, originating in 

 the bacteria, includes all the fungi ; the second type consists of unicel- 

 lular organisms, in which the cell-contents is comi^osed of pale, blue- 

 green endochrome without distinct chlorophjdl-grains, starch-grains, or 

 nucleus. The third series, and the only one which has developed into 

 higher forms of vegetable life, is characterized by cells containing chlo- 

 rophyll-grains, starch-grains, a nucleus, and usually a true cellulose wall. 



The last published part of Agardh's classification of algiie (Lunds 

 Univ. Arsskr., xxiii) refers to the Siphonew. He divides the whole 

 groilp into six families : (1) Bryopside;e ; (2) Spongodiere ; (3) Udotea- 

 ceaj ; (4) Valoniasea^ ; (5) Caulerpea^j (6) Dasycladej©. "Physiol, u. 

 alogologische SUidien," by Hansging, Prag., 1887, is a collection of the 

 author's papers published before on various algological topics. Mn)e. 

 A. Webea van Bosse has described (Nat. Verh. Holland. Maatsch der 

 Wettenschappen, Haarlam, 1887), the curious discovery of alga^ para- 

 sites in the hairs of sloths. Two new genera and three new species are 

 characterized. Potter (Journ. Linn. Soc, Lond., xxiv) has given ob- 

 servations on the curious algjv growing on the shell of the European 

 tortoise. Janse (Plasmolytische Yersuch. an Algen, Bot. Centralbl., 

 xxxii) shows that the living protoplasm in various alga? is permeable 

 to dilute solutions of mineral salts and cane sugar. The plasmolysis 

 completely disappears in two hours, and after four days the cells have 

 regained their former turgidity. " Zur Entwickluugsges einiger Con- 

 fervaceen," by Langerheim, is an interesting paper on the development 

 of confervacete. The sensitiveness of Spirogyra to shock is described 

 by Coulter (Bot. Gaz,, xii). He finds that when the filaments are cut 

 through with Oj sharp instrument, eight or ten cells nearest the point 



