484 KECORD OF SCIENCE FOR 1887 AND 1888. 



ALG^. 



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

 water Algte 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 

 Alga3, viz : Ehodophycete, chlorophyceie, and cyanophyceae, 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 i^olymorphism among alg« is given a prominent place. 



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

 modifications in the existing systems of classification of Alg;©, 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 composed of pale, blue- 

 green endochrome without distinct chlorophyll-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 algte (Lunds 

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

 group into six families : (1) Bryopsideae ; (2) Spougodieai ; (3) Udotea- 

 cete; (4) Valouiasea' ; (5) Caulerpene; (G) Dasycladete. "Pbysiol. u. 

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

 author's papers published before on various algological toi)ics. Mme. 

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

 Wetteuschappen, Haarlam, 1887), the curious discovery of algjc para- 

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

 chai.^cterized. Potter (Journ. Linn. Soc, Lond., xxiv) has given ob- 

 serva'tious on the curious alg* growing on the shell of the European 

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

 xxxii) shows that the living protoplasm in various algie is permeable 

 to dilut'e solutions of mineral salts and cane sugar. The plasmolysis 

 completej.v disappears in two hours, and after four days the cells have 

 regained th^ir former turgidity. " Zur Entwicklungsges einiger Con- 

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

 of confervaceae. The sensitiveness of Spirogyra to shock is described 

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

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



