88 SUMMARY OF CURRENT RESEARCHES RELATING TO 



highly developed host than the one on which it already grows is selected 

 by the parasite, and one of a more recent geological formation. He 

 divides the Uredinere roughly into two groups, the Melampsoraceae 

 and the Pucciniacese, the latter — the more recent in time — growing 

 almost exclusively on Angiosperms. Three factors are important in 

 influencing the selection by the parasite of new hosts : (1) the tendency 

 of the fungus to enlarge the circle of hosts ; (2) a corresponding con- 

 dition of the protoplasm of both plants, so that the host may receive the 

 parasite ; and (3) the geological age of the host plants. The writer 

 goes on to discuss the different genera of rusts, their probable age, and 

 the course of their development on the different hosts. Some of these 

 genera are confined to one family of host plants, others have attacked a 

 large number. The effect of temperature is also considered of great 

 importance in these changes. 



Relationship of Macrophoma and Diplodia.* — The pycnidia of 

 these two fungi were found growing in very close proximity on flower- 

 bud spathes of Cocos. Julia I. Emerson has proved, by a series of 

 cultures, that they are developmental forms of one fungus, and that the 

 colourless Macrophoma spores are immature stages of brown two-celled 

 spores of Diplodia epicocos. The cultures were commenced on agar, 

 and continued on potato and coco-nut pith or bread. 



Rotting of Cherries by Gloeosporium.f — A disease of apples caused by 

 a species of Glmosporium has been known for some time. A. Osterwalder 

 describes the effect produced on cherries by Glmosporium laeticolor. The 

 fungus appears on the fruits as small white pustules, which eventually 

 cause brown spots, and the wrinkling and shrivelling of the cherry. 

 The writer finds that the fungus can only penetrate the host through a 

 wound, but once entrance has been gained it spreads rapidly through the 

 flesh of the cherry. Systematic notes are given on several allied species 

 of Glaosporium. 



Leaf-disease of Ribes alpinum.J — R. Laubert finds that this disease 

 is caused by Glmosporium variabih sp. n. The leaves are irregularly 

 marked with round dark-coloured spots, on which the fungus is found 

 growing. Occasionally the fungus fruits on the green parts of the leaf. 



Morphology of a New Cytospora.§ — R. Laubert found a new 

 species of Cytosptora on half-dead gooseberry branches. The spores in 

 the mass have a golden yellow colour. The perfect fruit form, probably 

 a Valsa, was not found. A diagnosis of the fungus is given. 



Disease of Potato.|| — V. Tubeuf gives an account of early-blight or 

 eaf-spot disease which is caused by a Hyphomycetous fungus, Macro- 

 sporium = Alter naria Solani. On the same spots there appeared a 

 C 'ladosporium and a Sporidesmium. Joh. J. Vanhalf has made culture 



* Bull. Torrey Bot. Club., xxxi. (1904) pp. 551-4 (1 pi.). 



t Centralbl. Bakt., xi. (1903) pp. 225-6 (1 pi.). 



J Naturw. Zeitschr. Land und Forstw., ii. (1904) pp. 56-8. See also Ann. 

 My col., ii. ( 1 904 ) pp. 463-4. 



§ Centralbl. Bakt., xii. (1904) pp. 407-11 (1 pi.). 



]| Naturw. Zeitschr. Land, und Forstw., ii. (1904) pp. 264-9. See also Ann. 

 Mycol., ii. (1904) p. 465. 

 ' U Tom. cit., pp. 113-27. See also Ann. Mycol., ii. (1904) pp. 465-6. 



