ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 333 



He also * describes eleven new species of mosses collected in 

 Guadeloupe and Martinique by Prof. P. Duss. 



AlgSB. 



New Mougeotia.t — W. West describes Mougeotia immersa, a new- 

 species collected at Pokbaria, Cbota Nagpur, by the Eev. A. Campbell. 

 The zygospores vary in size from 30 /x. to occasionally 48 /x, and the 

 cells of the thallus are 20-24 /x across. 



Sexuality in Spirogyra.J — E. B. Copeland describes the various 

 degrees of sexuality to be met with in the different species of Spirogyra. 

 He gives an account of the conjugation of S. crassa, a dioicous species, 

 and calls attention to the effect produced in a cell that attempts to con- 

 jugate but fails. The nucleus was found against the wall opposite, but 

 remote from, the conjugating tube. The cell-contents lose their trans- 

 parency and become slightly granular with what may be oil-globules. 



Cladophora JUgagropilaJ — A morphological and systematic account 

 of the iEgagropila group of Cladophora is given by F. Brand, who has 

 made a study of this genus for many years. The material, on which 

 his investigations were made, was plentiful, and the species were culti- 

 vated by him both at home and in the open, thus allowing careful ob- 

 servations to be made under various conditions and in different stages 

 of growth. His results are described clearly under the following 

 headings: — Structure and growth of the vegetative filaments; Reversal 

 or mutability of polarity ; Organs of attachment (Rhizoids and Cir- 

 rhoids) ; Neutral shoots and " stolonids " ; Maintenance and propaga- 

 tion ; Conditions of life ; Aggregated forms. Dnder these headings 

 many points of interest are brought out, the chief of these being perhaps 

 the following, which have been specially emphasised by the author. 

 (1) The hydrophilous iEgagropila forms are typically rootless plants, 

 without polar division into a cauloidal and rhizoidal portion. (2) Their 

 accessory rhizoids can be developed from any portion of the plant and 

 in any direction. (3) Each species has a more or less constant limit 

 as to size, beyond which any increase is balanced by gradual dying-off 

 below. (4) By means of this regular withering of the oldest cells, the 

 lowest branches become regularly free in acropetal order. This may 

 also occur irregularly in all parts of the plant. (5) The iEgagropila? 

 have an extraordinarily slow growth and — like the Sphagna — an un- 

 limited period of life. (6) They require comparatively little light. 

 (7) The weak shoots, rather poor in chlorophyll, are not always rhizoids; 

 the character of such " neutral shoots " is at first doubtful and their 

 function is only determined by external circumstances. They may be- 

 come organs of attachment, or they may return to a vegetative condition. 

 The latter alternative may take place directly, or indirectly by the 

 formation of " stolonids." 



The morphological part of this paper is followed by a systematic 

 treatment of this group of Cladophora. The characteristic features of 

 the group as a whole are detailed, and it is then divided into two sub- 



* Journ. cit., xvi. (1902) pp. 6-11. t Jcrorn. Bot., xl. (1902) p. 144. 



% Bull. Torrey Bot. Club, xxix. (1902) pp. 161-3. 

 § Hedwigia, xli. (1902) pp. 34-71 (1 pi.). 



June 18th, 1902 z 



