364 Algae. 



Conrad, W., Note sur un etat filamenteux du Synum uvella 

 Ehrbg. (Bull. Soc. roy. Bot. Belgique. IL. 2. p. 126—132. 2 fig. 

 1912.) 



Tous les individus, et ils depassent generalement la eentaine, 

 sont inseres, en disposition tres serree autour d'un filament gelati- 

 neux, constituant un ensemble pouvant atteindre 260 et meme 300 

 M de longueur. Le filament de gelee sert ä tenir ensemble les 

 queues cytoplasmiques des individus et il n'est pas etranger ä ces 

 organismes. En annexe, l'auteur donne le releve des composants 

 du plankton lors de la frequence la plus forte de Synura avella. 



Henri Micheels. 



Delf, E. M., The Attaching Discs of the Ulvaceae. (Ann. Bot. 

 XXVI. p. 403—408. t. 45. 3 text-figs.) 



It seems probable that the adhesive discs of Ulva latissima are 

 very tenacious of life and persist through the winter even though 

 the expanded thallus dies away. The tubulär filaments forming the 

 disc were found to pursue a somewhat sinuous course, but they 

 never attained a lenghth of more than 3 mm. in the specimens 

 examined. The superficial cells giving rise to the filaments were 

 apparently always multinucleate. The tubes themselves were very 

 narrow and smaller when on the outside than when on the inside 

 of the thallus. Their apices were usually narrow and pointed until 

 some part of the periphery of the disc is reached, when the}' in- 

 crease greatly in size, and two or three successive segments with 

 usually more than one nucleus are cut off. 



In the case of discs of Ulva which were attached to a red alga 

 of the Polysiphoma-type , they had in many cases completely encircled 

 the host-plant, the walls of which were riddled with the small 

 pointed ends of the disc-filaments. The tips of these filaments had 

 in many cases expanded and almost filled the host-cell, and contained 

 a number of nuclei. The filaments were found boring their way 

 through the solid walls of the host-cells probably by means of an 

 enzyme. The author suggests that the Ulva is probably a facultative 

 parasite; and also, that the multinucleate character of the filaments 

 of the disc serves to emphasize the isolation of the whole group of 

 the Ulvales. G. S. West. 



Fritsch, F. E., Freshwater Algae collected in the South 

 Orkneys by Mr. R. N. Rudmose Brown, ofthe Scottish 

 National Antarctic Expedition, 1902 — 4. (Journ. Linn. 

 Soc. Bot. XI. p. 293-338. t. 10—11. 1 text-fig. 1912.) 



The total number of algae collected was 68 species, and a 

 comparison is made between them and those known from the islands 

 Kerguelen and South Georgia. 



Several samples ofyellow snow were examined. This occurs 

 in the wärmest season, but even then the mean temperature is not 

 above 32° F. The colour is very bright and the algae are on the 

 surface or extending into the snow to a depth of not more than 

 4 mm. Red and yeflow snow are quite distinct from each other. 

 Most of the algae of the yellow snow belong to the Protococcales 

 and there are amongst them several distinct types. For the most 

 part they include in their cellcontents a quantity of apparently solid 

 fat in large refractive lumps, and it is probable that the yellow 



