934 RECORD OF CURRENT RESEARCHES RELATING TO 



tlie whirls produced by the Vorticellce is supposed to be increased by 

 the presence in the immediate vicinity of the trichogyne of the forked 

 hair above mentioned. This hair, it is believed, will divide the 

 whirls, and thus produce subsidiary whirls, tending directly to bring 

 the antherozoids into contact with the trichogyne. 



In his conclusion, Prof. Dodel-Port makes the following remarks : 

 — " The total absence of active organs of locomotion in the antherozoids 

 of Florideae points to a common ancestor from which the diiferent 

 branches of the Florideae have inherited the immobility of the anthero- 

 zoids. During the differentiation of the red seaweeds many forms 

 have no doubt died out in consequence of fertilization not taking place 

 through the passivity of the male cells, while other forms have retired 

 to localities which favour the process of fertilization by the active 

 currents of the water in spite of the immobility of the antherozoids. 

 It is well known that we now find most of the existing species of 

 Florideae on the coasts of the warmer seas, which are constantly 

 washed by the waves ; while the northern coasts, which are covered 

 with crusts of ice during a great portion of the year, are very poor in 

 red seaweeds. Future researches will have to show how far in many 

 of these aquatic plants the differentiation of the genera took jilace 

 in the direction of an adaptation to the small marine animals which 

 inhabit them, and favour their fertilization in the way I have pointed 

 out." 



Cell-structure of Griffithsia setacea, and Development of its 

 Antheridia and Tetraspores.* — Professor E. P. Wright has made a 

 careful examination of this red alga, well known to all collectors of 

 seaweeds. In regard to the process of formation of the antheridia 

 and tetraspores. Dr. Wright observes, that at first they are hardly 

 distinguishable ; very early, however, the mass of protoplasm com- 

 pletely isolates itself in the former case, while in the latter it remains 

 attached by a little pedicel of protoplasm, which was found in every 

 species of Polysijjhonia in which he watched the development of the 

 tetrasporic fruit. After the mass of protoplasm is well formed, it 

 divides into four parts. Although the antherozoids of the FloridefB 

 are ordinarily described as motionless, Dr. Wright observed in those of 

 Griffithsia an obscure amoeboid movement, quite sufficient to enable 

 them to cling to or even enter a trichogyne. Various other inter- 

 esting points in the structure of the cells and in the production of 

 the sexual and non-sexual reproductive organs are described. 



Reproduction of Cutleria.f — A careful examination of Cutleria at 

 the zoological station at Naples, has led Falkenberg to confirm in the 

 main Eeinke's statements J as to its mode of fertilization. This is 

 not effected by a " diffusion-current," but by the actual coalescence of 

 a single antherozoid — presenting in this respect a contrast to Fucus — • 

 with the " receptive spot " of the oosphere. The attractive force of 

 the oosphere on the antherozoid appears to extend over a distance of 



* ' Trans. Irish Acad.,' xxvii. (1879) p. 27. 



t 'Mittheil. Zool. Station Neapel,' i. (1879) p. 420; see ' Bot. Zeit.,' xxxvii. 

 (1879) p. 510. 



X This Journal, ante, p. 605. 



