638 SUMMAEY OF CURRENT RESEA.RCHES RELATING TO 



Fung-i. 

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



Study of PhytophthorsB.* — W. Himmelbaur has made cultural 

 studies of Fhytopthora omnivora, a species determined by De Bary as 

 occurring on a large and varied series of host plants. He has compared 

 the appearance of the parasite on the different hosts one with another, 

 and has made cultures on agar which he fully describes. He finds three 

 different species included in P. omnivora, closely related, but with distinct 

 differences in the form of the mycelium, fructification, etc. He found also 

 that old and degenerate cultures bore a striking resemblance to the Vau- 

 cheriae. P. Syringse formed zones in the agar culture, but these were 

 caused by variations in the temperature. 



Spore-g-ermination and Infection in Comycetes.f — J. E. Melhus 

 made a series of experiments with the spores of Gystopus candidus. The 

 optimum germinating temperature was about 10° C, and water was a 

 more favourable medium than culture solutions. Infection took place 

 most surely at low temperatures ; at still lower temperatures the experi- 

 ments were unsuccessful, but it could not be determined whether this 

 adverse condition affected the spores or the host-plant. The fungus 

 was tested on several Cruciferje with negative results in many of the 

 experiments. 



New Species of Chgetomium.J — A. H. Chivers has been engaged 

 for a considerable time on a monograph of this genus, and he publishes 

 a preliminary series of new American species which he has been able 

 to cultivate and to examine in every stage of development. They were 

 obtained from very various substrata^several from dung, others from 

 paper, old cloth, etc. 



Biology of Rhytisma acerinum.§ — Karl Miiller has made infection 

 experiments with this fungus which occurs on the leaves of Acer plata- 

 noides, A. pseudoplatanus, and A. campestre, to see if biological races 

 had developed within the species. Spores taken from the fungus on 

 A. platanoides infected easily the same tree and also A. campestre, but 

 only sparingly A. pseudoplatanus The fungus on the latter tree 

 (Sycamore) is of smaller dimensions, and thicker than the one on 

 A. platanoides, but scarcely differs morphologically from the specimen 

 that resulted from the infection of the same tree hj the pseudoplatanus 

 fungus. Year after year, however, it infects strongly Sycamore leaves 

 only. Miiller designates this form as Rhytisma pseudoplatani. The 

 spores from A. campestre, the small-leaved Maple, infect also A. platan- 

 oides, though less readily, and will not grow on the Sycamore. The 

 author gives various details of experiments and of the different fungi. 



* Beih. Jahrb. Hamburg. Wiss. Anst., xxviii. (1911) pp. 39-61 (1 pi. and 11 figs.), 

 t Univ. Wis. Agric. Exp. Stat. Res. Bull. No. 5 (1911). See also Ann. Mycol., 

 X. (1912) p. 424. 



X Proc. Amer. Acad. Arts Sci., xlviii. (1912) pp. 83-8. 

 § Ber. Deutsch. Bot. Gesell., xxx. (1912) pp. 885-91. 



