281 SUMMAICY OF CURRENT RESEARCHES RELATING TO 



imuamcJ <Tecu alga: ami the niithor is of opinion that in the de- 

 velopment of tlie Clilorosporcas, stages occur which may be compared 

 to the coccus, bacillus, and even to the spiral forms of the Scliizo- 

 phyta ; while the formation of zoogloea-colonies is not an uncommon 

 phenomenon. This analogy in the vegetative development is the 

 more interesting, as between the Chlorosporeae and the CyanophyceaB 

 there is no such morphological agreement as between the Cyanophyceee 

 and the Schizomycetes. 



Anatomy of Macroeystis.* — During the German expedition to 

 South Georgia in 1S8-2-3, H. Will had the opportunity of carefully 

 examining the structure of the thallus of the gigantic seaweed Macro- 

 eystis lu.vurians, of which he found stems 70 metres long, and " leaves " 

 1 • G m. long, with an average diameter of • 27 m. The branching he 

 found to be of a sympodial and botrychoid character. The lamina 

 of the frond may be divided into three well-marked tissues, the 

 epidermal layer, the cortical parenchyma, and the hyi)hal tissue ; of 

 these the first is the seat of the chlorophyll-grains and of the brown 

 pigment. The air-cavity of the swimming-bladders is formed by the 

 swelling up of the " intercellular substance " in the middle of the 

 hyphal tissue. Within the hyphal bundles of the old stem new 

 elements make their appearance, including sieve-tubes. These have 

 horizontal sieve-plates with very large, polygonal, or roundish sieve- 

 pores, in some cases formed also on the side-walls. 



In the examination of a very large number of specimens, consisting 

 of all parts of the plant, and collected at all times of the year, the 

 author was quite unable to detect any organs of reproduction in 

 Macroeystis. 



Hibernation of Zygnemaceae.t — G. Schaarschmidt has observed 

 that the vegetative filaments of Zygnemacese (two species of Meso- 

 carpus and one of Spirogyra) have the power of retaining their vitality 

 through the winter. In the broken lumps of melting ice in a ditch 

 towards the end of INI arch, he detected jiale yellow or colourless balls, 

 the contents of the cells having shrivelled up in an irregular manner, 

 and the chlorophores almost lost their colour, as well as their special 

 spiral form in Spirogyra and disk-like form in Mesocarpus. In the 

 Spirogyra-CbMs were to be seen a few lenticular starch-grains in the 

 chlorophores, as well as pyrenoids. When placed in a warm chamber, 

 these cells showed signs of germination after the lapse of a few hours. 

 In Mesocarpus the protoplasm rapidly increased, and became attached 

 to the cell- wall ; the chlorophores assumed the form of a rounded 

 square, and the lamellaB increased slightly in length. In Spirogyra 

 the chlorophores assumed their characteristic form in the course of a 

 few hours ; but their colour was lighter than the normal. Cladophora 

 glomerata showed similar phenomena. It is probable that other algse, 

 including some of the filiform desmids, are able to hibernate in the 

 same way. 



* Bot. Ztg., xlii. (1884) pp. SOl-8, 825-30 (1 pi.), 



t Magyar Niivcn. Lapok, viii. (1884) pp. 33-7. t?ee Bot. Centralbl, xx. 

 (1884) p. 257. 



