1032 SUMMARY OF CURRENT RESEARCHES RELATING TO 



lamella of the cell- walls, and partially also the rest of the cellulose. 

 The destruction of the cell-walls is brought about directly by a 

 ferment, that of the protoplasm cither by a ferment or by acids or 

 salts dissolved in the cell-sap. 



The Peziza does not attack all plants alike ; those especially 

 liable are species of Petunia, Phaseolus vulgaris, Zinnia elegans, and 

 Daucus ; species of Helianthus and Solatium tuberosum to a less degree. 



The sclorotium of the hemp, caused by a species named by Tichomi- 

 row P. Kauffmanniana, is apparently identical with that of P. sclero- 

 tiorum, as also is probably that of the rape. Tho sclerotium-disease 

 which attacks cultivated clovers, especially Trifolium pratense, repens, 

 incarnatum, and hybridum, appears to be duo to a different species, 

 P. ciborioides Fr. (Selerotinia Trifoliorum Eriks.). 



Diseases of Crops.* — In the first part of an exhaustive work (in 

 Swedish) on the diseases of crops, Herr J. Eriksson gives special 

 descriptions of the following : — 



1. Gall-formations on the roots of barley. This is duo to the 

 attacks of nematoids. 



2. The rust of timothy-grass and oat. Caused by a fungus 

 apparently identical with Fuckel's Scolicotrichum graminis parasitic on 

 various grasses. 



3. Rose-rust. The recidial form of Phragmidium subcorticium. 



4. Mildew. The most abundant form of rose-mildew in Sweden 

 is Sphserotheca pannosa. Podosphsera oxyacanthse is also extremely 

 common on the hawthorn. Uneinula Aceris and U. Tidasnii occur on 

 the maple. The conidial stage of an undescribed mildew attacks 

 several species of Erica, e.g. E. gracilis, and is thus described: — 

 Oidium ericinum n. sp. Hyphi conidiophori solitarii, 60-80 li longi, 

 folia et caules ubique incolentes. Sporse ellipticae, utrinque rotundatae, 

 34-46 /x longa?, 12-16 //, lata?. On Acacia Lophantha the author finds 

 a new and jjeculiar form of Erysiphe Martii. 



5. The spot-disease of roses. Caused by Erysiphe radiosum. 



6. Apple-scurf. Fusicladium dendriticum. Occurring both on the 

 leaves and on the fruit. Pear-scurf is caused by F. pyrinum ; cherry- 

 scurf by a different species, which is thus described : — Fusicladium 

 Cerasi. Hyphasma supra epidermidem cerasi effusum, maculas 

 minutas orbiculares sericeas sordide cinereas in cute immersas 

 sistens. Hyj)hi assurgentes flavescentes, sirnjdices v. bifurci, tenuiter 

 septati. Conidia subelliptica, utrinque acuminata, 18-22 //, longa, 

 4 /x lata, simplicia v. uniseptata. 



7. Spot-disease on wild pears. Due to Xyloma Mespili DC. {Mor- 

 tluera Mespili Fkl.). 



8. Myrtle spot-disease. Caused by a new species, Cercospora 

 Myrii. Macula? epiphyllas, subrotundse, rufo-jmrpureae. Caespituli 

 hypophylli, fusciculati, fusco-atri. Conidia longissima, curvula, versus 

 apicem attenuata, cuspidata, fusca, 3-6-septata, 60-100 ll longa, 

 2-4 fx lata. 



* Eriksson, J., ' Bidrag till kiumedomen om vara odlade v'axters sjukdomar,' 

 No. 1, 85 pp. and 1 pi., Stockholm, 18S5. See Bot. Centralbl., xxvi. (1886) 

 p. 335. 



