674 SUMMARY OF CURRENT RESEARCHES RELATING TO 



!o be a Sepedonium ; like other species of that genus, it has minutely 

 echinulate spores. The other grew on fresh manure, and has been 

 diagnosed as a new species of Penicillium. 



Uredinese. — Ellsworth Bethel * publishes an account of sonic species 

 of Gymnosporangium, notably of two species that cause witches'-brooms 

 or fasciation of the branches : Gymnosporangium N'eUoni on Juniperus 

 scopulorum, and a new species Gymnosporangium Kernianum on 

 Juniperus Utahensis, which produces a compact spherical fasciation; 

 there, are no clues as to the aecidial form. 



J. W. Ellisf reports the finding of a rare Uredine, JEcidium leuco- 

 spermum, on Anemone nemorosa in N. Wales. No trace of Puccinia 

 fusca, the alternate form, was found. 



Jakob Eriksson | gives results of two years' work on the rust of 

 mallows, Puccinia Malvacearum. The propagation of the disease is 

 secured chiefly by the dissemination of infected seeds or of shoots grown 

 from such seeds. In the latter case the shoots remain healthy about 

 three months, then suddenly show disease with numerous pustules on 

 the leaves. A secondary eruption, which affects all the green parts of 

 the host-plant, arises from external infection. 



The fungus winters under natural conditions in stalks of Althaea 

 rosea as a mycoplasm in symbiosis wdth the protoplasm of the cells. 

 In pustules formed in autumn there are two kinds of spores morpho- 

 logically similar but differing in the mode of germination, some of them 

 forming a bent promycelium with sporidia, the others producing a long 

 straight filament which breaks up at the end into short cells or conidia. 

 Inoculation by promycelial sporidia results in the formation of a 

 filament which penetrates the palisade cells and then passes to the 

 intercellular spaces ; pustules of spores follow in 10 to 20 days. 



In the case of inoculation by conidia, the whole contents of the 

 conidium passes into the epidermal cell as a plasmic mass, spreads along 

 the cell-wall, and forms plasmic bands across the interior. It passes to 

 neighbouring cells until the whole leaf is occupied. Eor weeks there 

 may.be no trace of disease. The fungus passes from the plasmic to the 

 mycelial stage shortly before spore-formation. At that stage a free 

 nucleolus is constituted in the plasma of the cell round which the 

 mycoplasm collects. It then approaches the cell-wall, forms a pear- 

 shaped body, and passes into the intercellular space : there it forms a 

 filament. The same process takes place in a large number of cells ; the 

 newly formed mycelium grows and takes possession of the whole leaf, 

 and in 10 to 20 days forms spore sori. 



E. Baudys § records the many attacks of rusts in north-east Bohemia 

 during the year 1910. Great harm was done by Uromyces Fabae, U. Pisi, 

 and U. Trifoliirepentes, on various Leguminosse. Uromyces Betae attacked 

 beet plants, destroying all the leaves ; U. Pose appeared on several 

 species of Poa. On other grasses were noted Puccinia dispersa, P. bromina, 

 P. triticina, P. glumarum, P. graminis, etc. P. Pruni spinosx was so 



* Mycologia, iii. (1911) pp. 156-60 (1 fig. and 1 pi.). 



t Journ. Bot., xlix. (1911) p. 235. 



X Comptcs Rendus Acad. Sci. Paris, clii. (1911) pp. 1776-9. 



§ Zeitschr. Pflanzenkr., xxi. (1911) pp. 287-S. 



