358 Fungi, Myxomyceten, Pathologie. 



pineapple leaves, and pomelo {Cityus decurnana) skins is reported. 

 A cultural study of the fungus was made, and an emended descrip- 

 tion is given. Two distinct forms of cruciate conidia were found, 

 the one spiny and the other smooth. Hedgcock. 



Bioletti, F. T., Oidium or powdery Mildew of the Vine. 

 (California Agric. Station Bulletin CLXXXVI. p. 315-351. 17 fig 

 Febr. 1907.) 



The author gives a description of the powdery mildew {Uncmula 

 spiralis) giving its life history and its method of attacking the vines. 

 The conditions favoring the disease are described, and cultural 

 methods of control. The sulfur treatment for prevention is described 

 and recommended. Winter treatment is not recommended. 



Hedgcock. 



Blakeslee, A. F., Zygospores and Sexual Strains in the 

 common Bread Mold, Rhizopus nigricans. (Science, XXVI. 

 p. 119. 1906.) 



The writer gives a general account of the strains in spontaneous 

 zygosporic cultures of Rhisopus nigricans, and refers to the work of 

 Hamaker. A description is given concerning the influence of external 

 conditions on the formation of zygospores of heterothallic Mucors. 



H. von Schrenk. 



Butler, E. J., An Account of the Genus Pythium and some 

 Chytridiaceae. (Memoirs of the Dept, of Agric. in India. Vol. I. 



N'C 5. 160 pp. 10 Plates. 1907.) 



The memoir is divided into two parts, Part 1 of which being a 

 monograph of the genus Pythium. The second pari deals with a 

 number of species of Chytridiaceae, many of which are parasitic on 

 Pythium. 



After an historical survey of the work that has already been 

 done on Pythium, the author gives a general account of the genus 

 treating of its Distribution, Habit, Parasitism, Mycelium, and Repro- 

 ductive Organs. The latter are discussed in some detail, the different 

 Organs being treated separately and comparisons made between the 

 nature of these bodies in the different species. With regard to 

 parasitism the author states, that all the species that have been 

 investigated are capable of living saprophytically and that even the 

 most destructive Pythium de Baryanum attains its maximum deve- 

 lopment and reproductive activity, when cultivated as a saprophyte. 



A section is devoted to the phylogeny of the group in which 

 the various opinions which have been held with reference to the 

 fungus are summarized. The author himself believes, that a deriva- 

 tion of the main families of the Oomycetes through Moiioblepharis 

 and Leptomitaceae is most probable, though he expresses himself 

 with caution on account of the many gaps in our knowledge espe- 

 cially as to cytological details. 



As to the arrangement of the species previous methods are 

 departed from, and the genus is divided as foUows. 



I. Sub-genus Aphragmium. 



Sporangia filamentous, resembling the vegetative hyphae, not 

 separated off from the vegetative mycelium by septa, often branched 



