590 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the series was successful, those collected from wheat and transferred 

 to other wheat plants. The others gave only negative results. He 

 made a further series of experiments with wild grasses. He took the 

 Oidium spores from barley and infected a large series of pasture and 

 other grasses. The spores grew on the species of wild barley, but 

 failed entirely on all the other genera selected. There is no morpho- 

 logical difference in Eryxiplie graminis from these different hosts, but he 

 concludes that there are distinct physiological or biological races evolved 

 within the genus by gradual sj:>ecialisation on the various hosts. He 

 hopes in future to make further experiments with the ascospores. 



Parasitism of Botrytis cinerea.* — Ealph E. Smith gives an account 

 of this fuugus, usually a saprophyte, but also very frequently a mis- 

 chievous parasite. Instances are given of the direct infection of a living 

 leaf by the Botrytis conidia; but the writer considers that they grow 

 more readily when saprophytic nourishment is first supplied. After 

 infection, the neighbouring tissue is found to have been killed by the 

 action of the fungus, which then feeds on the dead cells. Smith con- 

 siders that there are two effects to be distinguished : first, the killing of 

 the tissue by some poisonous substance secreted by the fungus ; and 

 secondly, the disintegration of the cells by a variety of enzymes. 

 Botrytis was grown on a very large variety of substances. It was found 

 to grow well on sugars in general, on dextrin, cellulose, glycerin, gum 

 arabic, vegetable oils, tartaric and malic acids, asparagin and several 

 glucosides. An account is given of the changes induced in several of 

 these media by the growth of the fungus. The writer concludes that 

 the poison given off by the Botrytis is oxalic acid formed by the fungus 

 as a by-product of its metabolism. The conidia require saprophytic 

 nourishment to start them on their career as parasites, because they are 

 thus enabled to form a sufficient quantity of oxalic acid to attack the 

 host- tissue. It is pointed out that where infection has taken place from 

 conidia alone, these are always unusually large. 



Some North American Discomycetes.f — Elias J. Durand has found 

 a number of species hitherto only recorded from Europe. He gives full 

 descriptions from the fresh material. He has discovered two species 

 new to science. One of these, Ciboria americana, grows on the inside 

 of decaying husks of Horse-chestnuts. It is very like the European 

 G. echinophila, and may prove to be the American form of that species. 

 The other, Sclerotinia Smilacinse, resembles S. tuberosa. It grows from 

 small sclerotia which are attached to the decaying rhizomes of Smilacina 

 racemosa. 



Kryptogamen-Flora.J — The latest issue of this work, under the 

 editorship of Andreas Allescher, continues the account of the genus 

 Melanconium. It also includes the genera Cryptomela, Thyrsiclium, and 

 Basiascum, all with one-celled spores. The Hyalodidyinse come next 

 in order with the genera Marsonia, Septomyxa, and Glceosporiella. The 

 PLasodidyrnae are represented by Didymosporium and Bullaria, the latter 

 with only one species. Bhopalidium, also monotypic, Septoglceum, 



* Bot. Gaz., xxxiii. (1902) pp. 421-36 (2 figs.). 



t Bull. Torrey Bot. Club, xxix. (1902) pp. 458-65. 



J Kabeiiliorst's Krypt. Flora, i. Abt. vii. Leipzig (1902) pp. 577-640. 



