I9O BOTANICAL GAZETTE. [ August, 



The same would not have been expected in the case of 

 the Japanese Peronospora, for its aspect is unlike that of 

 most of the zoosporiferous forms placed by Schroeter in the 

 genus Plasmopara. The Japanese fungus is less conspicuous 

 to the naked eye than P. australis, and covers scattered spots 

 on the underside of the leaves with a thin down. The con- 

 idiophores are not densely tufted in the stomata, but are 

 either solitary or grouped in small numbers. They have an 

 average breadth of from 4-6/A and generally reach a height 

 of 25-30/x before they begin to branch. The ramification 

 is typically pinnate, the branches being given off at rather a 

 wide angle, but not at right angles as in P. viticola and P. 

 Halstedii. The main branches are again loosely once or 

 twice pinnate with straight, filiform, widely diverging tips. 

 Occasionally there is an appearance of forking, owing to the 

 exceptionally luxuriant growth of the lower branches, but 

 the typical branching is certainly pinnate rather than dichot- 

 omous. Compared with the conidiophores of other species the 

 present form is marked by its slender naked main axis bear- 

 ing a loose'tuft of branches near the tip. The spores are ob- 

 tusely oval, from 21-25/* l° n g by 15-18/* broad, 25/^ by 18/* be- 

 ing very common. They are slightly papillate and, when 

 mature, of a dingy violet color. Oospores were not seen by 



me. 



J a P 



curbitaceous plant besides Cucumis sativus, but I am unable 

 to give the name of the second host. 



Mr. Miyabe has fortunately been able recently to exam- 

 ine the specimens of Peronosfora Cubensis B. & C. in the 

 Berkeley collection at Kew, and finds that the Japanese fun- 

 gus is identical with that species. The species is interesting 

 biologically because, as a rule, the conidial spores of those 

 Peronospora^ which produce zoospores are small and cu- 

 boidal in shape, while the large oval and violet colored spores 

 of the present species suggest rather species placed by de 

 Bary in the section Pleuroblastae. The range of the species 



is also interesting. 



Wr 



New J 



J*P 



by Professor Halsted on cucumbers. The latter specimens 

 agree perfectly with those from Japan, and Professor Halsted 

 informs me that he has also been able to see the germination 

 of the conidial spores by zoospores, thus confirming the ob- 



Mass 



Japan by Mr 









