47G BTBLIOGEAPHT. 



drucktafel. Leipzig, A. Forstnersche Buclihandlung (Arthur 

 Felix), 1861. 



This treatise, as its title shows, relates to the well-known 

 potato disease, which the author, in couimon with other writers, 

 attributes to the action of Peronospora infestans, a mould which 

 Dr. de Bary states to be peculiar to the potato, and the allied 

 species of Solanum. Suggestions are given with regard to 

 the mode of cultivation, and other precautions which should be 

 adopted to ward off the disease, 

 Baut, a. de.— Ueber die Geschlechtsorgane von Peronospora. Bot. 

 Zeit. 5 April, .1861. Vol. xix. p. 89. 



The author states that he has observed in P. calofheca and 

 P. Alsinearum small curved clavate cells, springing from the 

 mycelium, which press with their upper end against the wall of 

 the large vescicular spore cells observed by Tulasne and Caspary. 

 He considers these latter cells to be 1-spored oogonia, and the small 

 clavate cells to be antheridia. The spore-cells in their early stage 

 exhibit an accumulation of granular matter in their interior, not at 

 first clothed by a membrane. As soon as this ball of granular 

 matter is formed, the antheridium emits a delicate prolongation 

 (similar to those of the antheridia of Saprolegnia), which pierces 

 through the wall of the oogonium, and reaches the granular ball. 

 The latter then becomes immediately clothed vnth a delicate 

 colourless membrane, and thus forms an oospore. The contents 

 of the prolongation are similar to those of the main body of the 

 antheridia, and no traces of spermatozoa are visible. The forma- 

 tion of the outer membrane of the oospore of P. Alsinearum from 

 the surrounding plasma within the oogonium is then described. 

 The ripe oospore is stated to possess a firm colourless cellulose 

 membrane inside the dark-brown outer one. The author con- 

 siders that his observations prove the possibility of the formation 

 of a cell-membrane directly out of proteine matter, and otherwise 

 than by secretion from the contents which it surrounds. 

 BoNORDEN.— Beitrage zur Mykologie. Bot. Zeit. July 12 and 19, 

 1861. Vol. xix. pp. 193, 201. 



Dr. Bouorden's papers contain descriptions of a number of 

 fungi considered by the author as new species. There are some 

 remarks upon the genus Cystopus, and upon the sj^ecific distinc- 

 tions of G. cuhicus and C. candidus, and a doubtful new Cystopus 

 occurring upon Alisma. He states that the plant figured as 

 Oidium Tuckeri by von Mohl, in Bot. Zeit. Vol. xi. No. 33, 

 plate 11, and as Oidium leucoconium by Preuss, in Sturm's 

 Deutschlaud's Flora, III. Heft. 29-30, Tab. 34, are both identi- 

 cal with his species Croeysporium fallax. Two new genera are 

 proposed, " Phacellium " (published in Eabenhorst's Fungi 

 EuropiiM, Cent. III. 288), belonging to the Isarieee, and distin- 

 guishable by its septate spores ; and " Polythecium," which is a 

 compound Cryptosporiiun. The new species described include 



