211] Phycomyceten, Plasraodiophoraceae. 297 



Die neue Art wurde an Aphiden in Gewässern bei Ithaca, N. York ge- 

 funden. Verf. studierte dieselbe genau und gibt folgende Zusammenfassung: 



1. The plant resembles in general the other species of the genus. Its 

 mycelium is definitely constricted, which fact, it seems, definitely places 

 the genus in the family Leptomitaceae. 



2. It possesses peculiar perforated pseudo-septa which are formed at the 

 constrictions, and which in a way are comparable of the „cellulin rings" 

 of other members of the Leptomitaceae. 



3. Zoosporangia are provided with a number of papillae of dehiscence 

 distributed over the surface, which are formed as the resvilt of the 

 gelatinization of small circular areas of the wall. The resulting plug 

 is made up of two district parts, the inner of which forms a vesicle 

 into which the zoospores escape at the time of their discharge. 



•i. The zoospores possess a large centrally located subtriangular mass of 

 apparently reserve food substance, probably proteid in nature, at whose 

 base is located the nucleus. The are typically uniciliated, withe the 

 cilium in direct relation to the nucleus. 



5. Resting sporangia possess a three-layered wall; the outer and inner layers 

 thin and hyaline; and the middle thick, perforated and orange colored. 

 After a period of rest of several weeks, germination takes place by the 

 formation of zoospores. 



6. On germination the zoospore produces a germ tube which forms the 

 basis of the rhizoid System, while the body of the spore becomes the 

 basal cell of the plant. 



7. Nuclear division is somewhat unusual, apparently, and reminds one of 

 amitosis. It seems to the writer, however, that it is more probably a 

 form of mitotic division dealin g with a Single large chromosome. 



1737. Becker, J. Über Kohlhernie. (Schleswig-Holst. Zeitschr. f. 

 Obst- u. Gartenbau, 1912, p. 3—5.) 



1738. Bottini, E. L, La Peronospora viticola. Contributo allo studio 

 delle cause interne che inducono una diversa resistenza dei vitigni 

 alla peronospora. (Agricolt. Ital. Pisa, 1909, Fase. 14, 8 pp.) 



1739. Bretschneider, A. Die falschen Mehltaupilze (Peronosporaceae) 

 und ihre Bekämpfung. (Monatshefte f. Landwirtschaft, Wien 1912, No. 5, 

 p. 138-147, c. fig.) 



1740. Bretschneider, Ä. über den Befall kultivierter Rosen durch 

 den falschen Mehltaupilz, Peronospora sparsa Berk. (Österr. Gartenzeitg., 

 Vn, Wien 1912, p. 223-226.) 



Peronospora sparsa befällt selten kultivierte Rosen, kann aber unter Um- 

 ständen in Glashäusern oder Sämlingsbeeten sehr stark auftreten. Verf. beschreibt 

 den Pilz. Bekämpfungsmittel werden genannt. 



1741. Bretschneider, A. Vergleichende Versuche mit einigen 

 Spritzmitteln gegen die Blattfallkrankheit des Weinstocks {Perono- 

 spora viticola De By.). (Zeitschr. f. d. landwirtsch. Versuchs wesen in Österreich, 

 XV, 1912, p. 147.)' 



1742. Campbell, Carlo. L'infezione peronosporica nell 1910. (II 

 Coltivatore, Casalmonferrato, LVL 1910, p. 427-429.) 



1743. Cavazza, D. Conclusioni nellalotta contro la peronospora. 

 (Italia agricola, Piacenza, XLVII, 1910, p. 493—495.) 



