336 SUMMARY OF CURRENT RESEARCHES RELATING TO 



an hour, the formation of zoospores, which germinated fifteen minutes 

 late)'. On the surface of the leaf the process might be a little slower. 

 The germinating spore penetrates only on the under surface of the leaf. 

 When the conidia have been sown on the upper surface, the zoospores 

 make their way, by means of the thin sheath of water covering the leaf, 

 to the lower surface ; the leaf is always attacked near the edges. 

 Spraying with Bordeaux mixture, by covering the upper surface with 

 copper, prevents the germination of the conidia and the passage of the 

 zoospores to the under side. 



Thraustotheca clavata.* — - This member of the Saprolegniaces, 

 formerly known as Dictyuchus, was found by W. C. Cohen and 0. "W. 

 Hyman, and was kept under observation by them for some time. The 

 formation of sporangia, oogouia and antlieridia was observed, but no 

 sexual fusion was noted. The male and female organs arose from 

 different hyphae. 



Viability of Pyronema Spores. t — F. J. Seaver states that this fungus 

 is common in America, and can easily be secured and cultivated by ex- 

 posing prepared plates. The spores remain capable of germination for 

 nearly three years and possibly longer. 



Spore Formation in Podospora anserina.|^ — Fred. A. Wolf was led 

 to study this species, as only four spores are contained in the mature 

 ascus, and such an ascus has not been previously examined. The peri- 

 thecia arise from hyphal coils, which probably indicate sexual cells, but 

 no fusion was observed and the nuclei are extremely minute. After the 

 perithecium is formed the asci arise in tufts : several were seen to branch 

 from one hypha. The cells of the perithecial wall, of the paraphyses, 

 and of the vegetative mycelium were multinucleate. The ascus contains 

 at first one lai'ge nucleus ; the first two divisions follow each other 

 rapidly, and are probably heterotypic and homotypic. After the second 

 division there is a resting period, and an increase of the nuclei in size. 

 A third division gives eight free nuclei in the ascus. In each spore two 

 of these nuclei are included. Wolf thinks that possibly only one of the 

 nuclei takes part in the formation of the spore wall. 



The Brown Leaf-spot of Colt's-foot.§— Fred. A. Wolf made cultures 

 of the fungus Ramularia brunnea, that forms brown spots on the leaves 

 of Tussilago farfara. He put the affected leaves in wire cages and left 

 them out of doors during the winter. Wolf had obtained only conidial 

 stages in his artificial cultures, but on the leaves themselves there 

 developed in spring small perithecia which proved to be those of 

 Sphserella tussiJaginis, the ascigerous stage of the Rarmdaria fungus. 



Pyronema confluens.|] — P. Claussen has made an exhaustive study 

 of the development of the fruit in this fungus. It was cultivated on 

 agar-agar, fixed, embedded and stained, the different processes being 



* Mycologia, iv. (1912) pp. 87-90 (1 pi.). 



t Bull. Torrev Bot. Club, xxxix. (1912) pp. 63-7. 



+ Ann. MvcoL, x. (1912) pp. 60-4 (11 figs.). 



§ Ann. Mycol., x. (1912) pp. 65-7 (7 figs.). 



Jl Zeitschr. Bot., iv. (1912) pp. 1-64 (6 pis. and 13 figs.). 



