436 SUMMARY OF CURRENT RESEARCHES RELATING TO 



which pass the winter at the bottom of the water. In the species 

 studied here, the daughter nuclei in the zoosporangia are disposed 

 alternately along the main axis of the body. In another and closely 

 allied species the division of the primitive nucleus takes place in an 

 equatorial plane, and the individuals are grouped in the zoosporangium 

 in a parallel spiral bundle. 



Myriactis Areschougii and Coilodesme californica.* — M. Rath- 

 bone describes briefly the work hitherto done on M. Areschougii Batters, 

 especially that of Mons. Sauvageau. She has been unable to trace the 

 infection of the host-plant or the early stages of the parasite, as in the 

 early months of the year the thallus of the host- plant, Himanthalia 

 lorea, is invaded by the filaments of numerous penetrating algae. 

 M. Sauvageau suggests that infection takes place by means of zoospores 

 which germinate in the cryptostomata or conceptacles ; but the author 

 finds no connection between these bodies and the mature plants of 

 M. Areschougii. The rhizoids travel for long distances in the tissue 

 of the host and probably act as stolons for propagating the plant, as in 

 M. stellulata. In fresh material the rhizoids are easily distinguished by 

 their pinkish-brown colour, and in spirit material they stain more deeply 

 with Hoffman's blue than do the host-cells. Active cell-division of the 

 host-cells is often seen below and around the tufts of the parasite, and 

 these host-cells take a rather different stain with Hoffman's blue from 

 that of the surrounding tissue. Mucilage occurs chiefly at the base of 

 the hairs and round the assimilating filaments, but is also found far 

 down in the cushion of the parasite. The penetrating rhizoids of 

 Coilodesme californica Kjellm., are also described, which have hitherto 

 been overlooked in descriptions of the plant. These rhizoids form a 

 dense mass in the substance of the cell-walls of the host, and seen in 

 longitudinal section they have a curiously opaque and ribbed appearance. 

 Figures are given of the rhizoids of both plants, and also of the pluri- 

 locular sporangia of Myriactis stellulata, figured and described by 

 Harvey in his Phycologia Britannica as " paranemata." 



Sphacelariacese.f — C. Sauvageau continues his treatment of this 

 order and deals with Halopteris Novce-Zelandioe Sauv., of which he 

 gives a long description, the formal diagnosis and figures. He also 

 describes and figures H. obovata Sauv. = Sphacelaria obovata Hook, fil- 

 et Harv., and H. platycena sp. n., which he describes and figures. 



New Genus of Corallinacese.J — F. Heydrich has succeeded in 

 finding the antheridia of Lithophyllum expansnm Phil., and since these 

 occur on different plants from the cystocarps or tetraspores, the author 

 founds for this species a new genus, Stereophyllum. He recognises two 

 forms, f. stictceformis Aresch. and f. agariciformis Hauck., of which he 

 gives short diagnoses. The principal characteristic of the vegetative 

 thallus is the absence of a " co-axile stratum," the cells of the entire 

 thallus ascending in straight lines to the surface. This constitutes a 

 difference between Stereophyllum and other species which resemble it in 



' * Journ. Linn. Soc. fBot.) xxxv. (1904) pp. 670-5 (1 pi.). 

 t Journ. de Bot., xviii. (1904) pp. 88-104 (5 figs, in text). 

 % Ber. Deutsch. Bot. Gesell, xxii. (1904) pp. 19G-9. 



