82 SUMMARY OF CURRENT RESEARCHES RELATING TO 



host-plant with water-containing zoospores, and produced all the symp- 

 toms of the disease. The author gives advice as to the stamping out of 

 the disease, which he thinks should he easily done by avoiding all 

 wounding of the hark and, as far as possible, all contact between the 

 young twigs and the soil. 



V. Ducomet* gives an account of his research on diseases of 

 cultivated plants. He cites, first of all, a new parasite of rye-grass, 

 Fusarium loliaceum, which lives on and destroys the leaves. The author 

 finds it growing in a more sparse manner than is usual with Fusarium, 

 but he finds that the two conditions of scattered and compact formation 

 of conidiophores is a growth state, and not a generic difference. 



He records a new disease of pine-leaves caused by a minute Asco- 

 mycete, Sphserella pmifolia sp. n. It encrusts the needles with brown 

 hyphse, and chokes the stomata ; later, the hyphas penetrate the tissues. 



A new disease of potatoes has also been discovered by Ducomet, and 

 ascribed by him to a fungus — probably Vermicularia varians. The 

 fungus forms minute sclerotia on the tuber ; the fungal filaments 

 collect in the superficial tissues, and form hardened surfaces. Notes 

 arc also given on the oak mildew. The writer agrees that it cannot 

 be Microsphaera Alni, and that it is probably distinct from Oidium 

 quercinum. 



H. T. Gussowf reports on black-scab of potatoes in Newfoundland. 

 Be gives a history of the disease in Europe, describes its appearance, 

 and suggests remedies. He accepts the name given by European 

 mycologists, ChrysopMyctis endoMotica. 



Root-fungi of Orchids.:}: — Hans Burgeff has studied the fungi 

 that enter into symbiotic relationship with orchid roots, and now pub- 

 lishes the results of his observations and experiments. He discusses the 

 meaning of symbiosis, and combats Elenkin's theory that of the two 

 symbionts one is necessarily living at the expense of the other. The 

 two organisms are really well-balanced in nature ; and only when, by 

 some accident, one becomes overweighted, does harm result to one or 

 both of the symbionts. 



Burgeff describes the morphology and physiology of the fungi from 

 data gained in his experiments. The fungus does not assimilate free 

 nitrogen, and it is aerobic ; formation of spores and sclerotia depend on 

 the concentration of the substratum. In the second part of the work 

 he describes the result of cultures of orchids from seed with and with- 

 out the fungus symbiont, gives detailed accounts of many of the orchids 

 and the root-fungi, and discusses from every standpoint the value and 

 function of the mycorhiza, 



Bbbgamasgi, G. — Due nuovi miceti per la campania. (Two new fungi for 

 Italy.) 



[Montagnitcs Candollei and Gyrophragmium Dclilei were found, and are fullv 

 described. Nuovo Giorn. Bot. Ital., xxi. (1909) pp. 439-42 (1 pi.). 



* Ann. Ecole Nat. Agric. Rennes, ii. (1908) 1909, pp. 1-54 (54 figs.). See also 

 Bot. Centralbl., cxi. (1909) pp. 545-6. 



t Dept. Agric. Centr. Exper. Farm, Ottawa, Canada, Bull. No. 63, 8 pp. (2 pis. 

 and 1 fig.). \ Jena: Gustav Fischer, 1909, 250 pp. (22 figs.). 



