198 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Stbasburge;r, E. — Zur Frage Eines Generationswechsels bei Phaeopbyceen. (On 

 the question of alternation of generations in Phseophycese.) 



[Treats of the subject from the point of view of the changes in the nuclear 

 structure.] Bot. Zeit., lxiv. (1906) pp. 1-7. 



Tobler, F. — TTeber Regeneration und Polaritat sowie verwandte Wachsthums- 

 vorgange bei Polysiphonia und anderen Algen. (On regeneration and polarity, 

 as well as allied phenomena of growth in Polysiphonia and other algae.) 



Jahrb. Wiss. Bot, xlii. (1905) pp. 461-502 (3 pis.). 



Walker, N. — Pond Vegetation. 



[A study of the vegetation in ponds near Bramhope, Leeds. In addition to 

 the Phanerogams, were found abundant plankton — Peridinum tabulatum 

 and Cyanophycese ; also in winter occurred associations of QSdogonium 

 and Tribonema ; and in summer of Mougeotia, Spirogyra, Tolypothrix, 

 Anabcena, Phormidium, Microcystis.'} 



Naturalist, No. 585 (1905) pp. 305-11. 



Yendo, K. — Plankton Diatoms of Misaki. [In Japanese.] 



Bot. Hag. Tokyo, xix. (1905) pp. 257-65. 



Zernov, S. — Sur le cbangement annuel du plancton de la Mer Noire dans le baie 

 de Sebastopol. (On the annual change of plankton of the Black Sea in the Bay 

 of Sebastopol.) Bull. Accad. I. Sci., St. Petersbourg, ser. 4, xx. (1904). 



Fungi. 



(By A. Lorrain Smith, F.L.S.) 



Marine Phycomycetes.* — H. E. Petersen presents a study of Chytri- 

 dineae parasitic on various marine algse, most of which he has collected 

 and examined himself. As a rule, the only stage recognisable in the 

 specimens is the sporangial stage, and it is extremely difficult to follow 

 the development, as the zoospores die off in the cultures, partly, no 

 doubt, on account of the different conditions between the open sea and 

 the culture tanks. Petersen collected on the coast of Denmark and 

 further north. He found specimens most readily in quiet water 

 where the force of the waves was less powerful. He reviews in all 25 

 species, which he groups under two divisions : Monolpidiaceas, Eurychas- 

 macese, and Merolpidiaceas under Myxochytridina^ ; Holochytriacese and 

 Sporochytriacese under Mvcochytridinae. 



Studies in Erysiphacese.f — E. S. Salmon publishes a paper on 

 endophytic adaptation shown by Erysiphe graminis under cultural con- 

 ditions. This fungus has always been regarded as a strict ectoparasite, 

 the hyphas of the mycelium being confined to the external surface of the 

 epidermis, and merely sending haustoria into the epidermal cells. On 

 sowing conidia of the fungus on a wounded portion of a leaf, he 

 found that the fungus had grown down into the tissues of the leaf, as 

 far as the lower epidermis. Patches of conidiophores were formed on 

 the surface of the wound, and conidiophores were also produced in the 

 intercellular spaces. They grew usually in a vertical position, but in 

 some cases they were seen in a horizontal position. The writer suggests 

 that other species of Erysiphacese, while normally ectoparasites, may take 

 advantage of wounds or punctures to penetrate the leaf. 



* Overs, k. Danske Vidensk. Selsk. Forh., No. 5 (1905) pp. 439-88 (11 figs.), 

 t Phil. Trans., Series B, cxcviii. (1905) pp. 87-97. 



