ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 215 



A New Ghlorella.* — H. Kufferath has studied the nutrition of 

 ChloreUa by means of organic bodies. The species experimented on 

 was C. luieo-viridis Chod. var. lutescens Chod. Experiments have 

 been carried out in different nutritive liquids, the composition of 

 which is described. The author has remarked that, in different soki- 

 tions, Chlorella may vary within limits both as regards form and 

 dimensions. The greatest modifications of dimensions takes place in 

 carbohydrates and gums. They are much more pronounced in light 

 tluin in darkness, and are principally in the form of growth. The 

 form, under certain conditions which are described, may become ovoid, 

 irregularly polyhedral, or pear-shaped. The author discusses also the 

 reserve substances of ChloreUa, when cultivated in a sugar solution. 

 Under these conditions the pyrenoids, which are normally sufficiently 

 constant to serve as a basis for classification, may disappear and give 

 place to glycogen. This first accumulates round the pyrenoids, then in 

 the chromatophores, and is capable of giving rise to oily drops, if ex- 

 terior conditions become less favourable to the life of the alga. A 

 very complete bibliography is appended concerning the organic nutrition 

 of Algffi. . 



Microthamnion.t — J. Greger describes the development and repro- 

 duction of the genus Mkrothamnion. For want of knowledge of its 

 method of reproduction, its systematic position has been uncertain. 

 Various authors have placed it in Ulotrichaceae, Chroolepidacea3, and 

 Chsetophoracege. The author establishes its position in the last of 

 these orders. His results are as follows : — Microthamnion forms small 

 pale-green clumps plentifully and irregularly branched, either di- or 

 trichotomously. Branches stiffly erect, adpressed or free. Cells 3-6/a 

 wide, up to twelve times as long. Membrane very thin and unstratified. 

 Chromatophore pale-green, ribbon-shaped, and lying against the cell- 

 wall. Pyrenoids wanting. Nucleus single. Oil is formed as a product 

 of assimilation. Reproduction takes place by macrospores, from which 

 the young plantlets arise direct without previous copulation. The 

 dividing membranes of the lateral branches from the main stem are not 

 at the point of junction, but are formed somewhat higher in the lateral 

 branch by successive growth. The macrospores are long and pyriform, 

 possess two cilia of equal length, a pale-green chromatophore and a red 

 eye-spot. Under certain conditions (lack of water, etc.) a formation of 

 akinetes takes place. Finally, the author compares Microthamnion 

 with Fleurocorcus, Stigeocloninm, and LeptoHra. He recommends 

 caution in determination of species. 



Diatoms of Finland. J— A. Cleve-Euler makes new contributions 

 to the Diatomaceous Flora of Finland. The diatoms of that country 

 were worked out in 1891 by P. T. Cleve, since which time very few 



* Rec. lust. Bot. L6o Err6ra, ix. (1913) pp. 113-319 (4 pis. and figs.). See also 

 Bull. Soc. Bot. France, Ixii. (1915) pp. 86-8. 



t Hedwigia, Ivi. (1915) pp. 874-80 (1 pi.). See also Bot. Centralbl., cxxxi. 

 (1916) p. 78. 



J Arkiv Bot., xiv. (1915) 81 pp. (4 pis.). See also Bot. Centralbl., cxxxi. 

 (1916) p. 4. 



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