498 SUMMARY OF CURRENT RESEARCHES RELATING TO 



T. Eriksson * has made a new series of experiments with crown rust,, 

 Puccinia coronata and P. coronifera. In the latter species (related to 

 JEcidium catharticse) he has traced eigjit form species on different 

 grasses. In P. coronata (JEcidium Frangulse) he determined three 

 form species. His results agree with those of Klebahn, but not entirely 

 with Carleton's. The form species seem to be less sharply defined in 

 North America. 



Culture experiments have been made by 0. Juelf with Uromyces 

 Pose. He has determined nine forms, growing on different grasses and 

 species of Ranunculus. 



B. Ivanoff + has studied at Berne and on the Faulhorn the 

 different effects of temperature, etc., on the development of Uredinere. 

 The period of incubation depends on external conditions to a consider- 

 able extent, growth being more rapid in the sunlight than in the shade. 

 In the cold of the mountains, or in chambers filled with ice at Berne, 

 uredospores and teleutospores developed simultaneously. The peridial 

 cells of P. gr ((minis on Berber is varied in size according to their exposure 

 to sun or shade. 



Conditions of Sclerotium-formation in Botrytis =cinerea.§ — W. 

 Reidemeister grew this fungus on a series of culture media with 

 varying salt constituents and under varying conditions of light, 

 moisture, etc. He found that sclerotia were formed in all con- 

 ditions that were favourable to the growth of the mycelium. They 

 reached a size of 5-8 mm. in diameter, and the numbers formed 

 depended on the amount of nourishment supplied. There was con- 

 siderable variety in the location of the sclerotia : thus ou potassium- 

 nitrate-dextrose-agar, they were scattered over the substratum, and on 

 plum-juice-agar they were formed in regular rings, the latter con- 

 dition being less favourable to their development. The formation of 

 sclerotia in any of the media could be brought about by introducing 

 some foreign body which obstructed the onward growth of the 

 mycelium. At that point sclerotia were formed. If narcotics were 

 introduced into the atmosphere of the culture, sclerotia were encouraged. 

 Or, again, if the mycelium were allowed to grow over alternate layers 

 of thicker and thinner nutriment, sclerotia were formed on the thin 

 layers. Experiments were also made on conidial formation, it being 

 most abundant where transpiration was most active. "Where conidia 

 were abundantly produced, sclerotia formation lagged behind. Ap- 

 pressoria were developed under conditions favourable to the growth of 

 sclerotia. Tables are given representing the culture media with the 

 percentages of salts, etc., and the corresponding developments of 

 sclerotia and conidia. 



Xylaria polymorpha.|| — F. Gue'guen records his experience in the 

 culture of this fungus. Cooked carrot was found to be the best 



* Ark. Bot., viii. (1908) No. 3. See also Ann. Mvcol., vii. (1909) p. 197. 



t Svensk. Bot. Tidskr. ii. (1908) pp. 1G9-74. See also Arm. Mycol., vii. (1909) 

 p. 197. 



X Perioditchesko spissanie", lxviii. (1908). See also Bot. Centralbl., ex. (1909) 

 pp. 335-6. § Ami. Mycol., vii. (1909), pp. 19-44 (3 figs.). 



II C.R. Soc. Biol. Paris, lxvi. (1909) pp. 124-5. 



