ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 77 



Alternation and Parthenog-enesis in Padina. — J. J. Wolfe 

 {Elisha Mitchell Sci. Soc, 1918, 34, 78-109, 1 pL, tables). An account 

 t»f fxperiments carried out on Padina varienata Tickers, with a view to 

 duplicating the work of W. D. Hoyt on Didtjota. The same metliod 

 was adopted as in Hoyt's work, cultures beins; started in aquaria and 

 ti'ansferred later to the harbour at Beaufort, X.C. The development of 

 the various cultures is described in detail, and is also set forth in tabular 

 form. The author summarizes his results as follows :— 1. Tetraspores 

 produce only male and female plants. The nnmbers are approximately 

 equal, even when the spores are from the same plant and grown on the 

 same shell. Sex is therefore predetermined, probably, in the reduction- 

 division of the tetrasj)ore mother-cell. 2. Eggs when fertilized produce 

 tetrasporic plants only. There is thus an alternation of a sporophyte 

 generation which is an entirely distinct individual, with the gametophytic 

 generation consisting of two separate plants, the one bearing eggs, the 

 other sperms. 3. Unfertilized eggs divide freely, producing a cell-body 

 of varying size, which however invariably fails to mature. There is thus 

 in Padina parthenogenetic germination, bnt no parthenogenctic repro- 

 duction. E. S. G. 



Marine Algae of Guernsey. — Lilian Lyle {Journal of Botany, 

 1920, 58, Supplement II., 53 pp., 6 figs.). This paper consists 

 of a list of the marine algee of the island, together with an account 

 of certain ecological factors, a discussion of types in relation to 

 habitat and climate, economic uses, etc. A summary of previous lists is 

 followed by a systematic enumeration of all the known species, collected 

 by the author and others. The total number recorded is 350 species 

 and 78 varieties and forms, including many novelties for the Chamiel 

 Islands, a few for Britain, and one species and one form new to science. 

 The list contains a few critical notes on the structure, development, 

 habitat, distribution, systematic value, etc., of certain species founded 

 on the author's observations. In the section devoted to ecological 

 factors she describes the physical position of the island, tides, currents, 

 nature of the substratum, configuration of the coast, salinity, and 

 temperature. Four distinct types of vegetation are found, which 

 coincide in each case with certain climatic conditions ; the dominant 

 species of each are given and each type is discussed. The zones or belts 

 are distinctly traceable, though they vary considerably in width and 

 occasionally even disappear. Each zone is discussed separately, and the 

 littoral algse and lichens are set out in tabular form. Under the head- 

 ing " Composition of the Flora " the two elements of the marine vegetation 

 are pointed out : the northern, which is derived from the North Atlantic 

 and extends to the Norwegian Polar Sea ; the southern, which includes 

 species. from the Mediterranean, Indian Ocean, Brazil, W. Indies, etc. 

 The species representing both elements are enumerated. Finally, a 

 section is devoted to economic considerations. Up to the present only 

 two portions of our coast have been treated from the ecological point of 

 view : Clare Island and the neighbouring shores of Clew Bay, by Mr. A. D. 

 Cotton ; and Guernsey in the present paper. E. S. G. 



Studies of Algse of the Adriatic. — Y. Schiffner ( Wiss. 

 Meeresunters. N.F. Abt. Helgoland, 191(3, 11, 129-98, 133 figs, in text; 



