128 SUMMARY OF CURRENT RESEARCHES RELATING TO 



a kind of oval basidium, 7-8 /x long and 5-6 • 5 /x broad. The fungus was 

 cultivated for several generations without producing any but the conidial 

 form. 



Diseases of Cultivated Plants.* — Dr. E. Eostruji has observed, in 

 several places in the neighbourhood of Copenhagen, a hitherto undescribed 

 fuugiis parasitic on bairley, to which he gives the name Scolecotrichum 

 Eordci, nearly allied to S. graminis. The disease takes the form of white 

 strips on the leaves and stem. These strips are covered by fine grey dots 

 which are masses of hyphae projecting through the stomata. Each hypha 

 bears a single, comparatively large, oblong, light yellow, bilocular conidium. 



A Mhizoctonia was found to bo a very widely spread enemy of clover, 

 Medicago saliva, M. lupulina, Rumex, and Geranium. On clover plants from 

 Norway a new species, Typlada Trifolii, was detected, and a Mhizoctonia on 

 the potato. 



Diseases caused by Fungi. | — Dr. E. Eostrup groups under the name 

 " mycocccidia " the diseases of the nature of hypertrophy of tissue caused 

 by parasitic fungi. As a general rule the Myxumycetes (Plasmodiophora 

 and Schinzia) give rise to excrescences on the stem and roots. The Perono- 

 sporefe cause curvature of the stem and patches on the leaves. 



The author also describes the following new species : — Physoderma 

 deformans on the flowers of Anemone nemorosa ; Taphrina Tormentillse on 

 Tormentilla erecta ; T. JJmhelUferarum on Heracleum Sphondylium and 

 Peucedanum jialustre ; Fusariiim amenti on the catkins of Salix cinerea and 

 aurita ; and Exobasidium Oxycocci on Oxycoccus palustris. 



Asteroma of the Rose.f — Herr B. Frank describes the disease caused 

 by this parasite in rose jilantations, which differs from both the mildew and 

 rust of roses. It manifests itself in circular dark greyish-brown spots, 

 about 1 mm. in diameter, scattered over the whole u^jper surface of the 

 leaf. The species is Asteroma or Actinonema radiosum Ft. It is dis- 

 tinguished by its radiating filaments which run beneath the cuticle, become 

 septated and branched, and thence penetrate into the internal tissue of the 

 leaf. The fructification is formed beneath the cuticle in the form of minute 

 dark dots. The spores are from 0'0I5 to 0*018 mm. in length, two- 

 celled and colourless, and germinate directly. The injurious effect of the 

 parasite is shown in the formation of a brown or yellow resinous mass or of 

 drops in the epidermal cells, the adjacent cells of the parenchyma also 

 perishing. The disease sometimes extends to the under side, and the spores 

 are very readily carried by rain or dew, 



Gnomonia erythrostroma, a cherry-parasite. § — Herr B. Frank has 

 investigated the cause of a disease which is exceedingly destrixctive to 

 cherry-trees on the Lower Elbe, taking the form of yellow sjDots on the 

 leaves, which gradually increase in number and size, causing the leaves to 

 die without falling off, and finally killing the tree. He finds it due to the 

 attacks of a parasitic fungus, Gnomonia erythrostroma Fkl. (Sphseria ery- 

 throstroma Pers.). The perithecia ripen in the spring, when the asco- 

 spores, of which eight are formed in each ascus, are violently thrown out of 

 the asci in the same way as in Chsetomium, this being the mode in which the 



* In Danish, Copenhagen, 1886. See Bot. Centralbl., xxviii. (1886) p. 106. Cf. 

 this Journal, 1886, p. 299. 



t Bot. Tidsskr Kjobenhavn, xiv. (1885) pp. 21-6. See Bull. Soc. Bot. France, 

 viii. (188(i) Rev. Bibl, p. 99. 



X Frank, B., ' Deb. d. Rospn-Astcronia, einen Vcrniehter d. Rosenpflanzungen,' 

 1885 (16 pp. and 5 figs.). See Bot. Centralbl., xxvii. (188G) p. 294, 



§ Ber. Deutsch. Bot. Gescll, iv. (1886) pp. 200-5. * 



