ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 339 



two organisms live together, but shortly before the death of the leaves 

 poisoning effects are visible. 



The fungus winters in the rhizome. The haustoria in the cells 

 increase and branch, forming a clumjj of hyphae, almost of plecten- 

 chyma, within the cell. 



Development of Endophyllum Sempervivi.*— A. W. Hans Hoff- 

 mann has followed the development of this Uredine. Besides spermo- 

 gonia there are only aecidia formed. The tecidiospores functioning as 

 teleutospores germinate to form a promycelium and sporidia. From the 

 sporidium are produced hyphffi with uninucleate cells representing the 

 gametophyte. Tlie spermogonia, with their spermatia and the aecidia, 

 arise from these hyphse. The function of the spermatia is unknown. 

 At the base of the fecidium the wall between two uninucleate cells 

 becomes dissolved, and a fusion cell with conjugate nuclei is formed, the 

 first stage of the sporophyte. After conjugate division, the basal cell 

 cuts off the spore-mother-cell, which then divides into the dividing cell 

 and the spore : each of these cells contains two conjugate nuclei. In the 

 spore the two nuclei fuse, and the fusion is followed in the spore or in 

 the promycelium by a reduction division, of which the details, number 

 of chromosomes, etc., are still obscure. The promycelium, as a rule, 

 consists of four cells, each with a reduced nucleus ; from each of these 

 cells arises a sporidium containing a single nucleus. These changes 

 represent a true alternation of generations. 



Uredinese. — 0. Trebouxf gives an account of experiments with 

 rusts. He found that an tecidium on Ranunculus iUyricus infected plants 

 of Festuca ovina, producing uredospores and teleutospores of Uromyces 

 Festucse. ^cidia on Sium lancifoUum produced the teleutospores of 

 Uromyces lineoJatus on Scirpiis maritimus. He found uredospores as 

 well as teleutospores belonging to Uromyces Ficarise on the leaves of the 

 celandine. Uromyces Astragali was associated successfully with an 

 aecidium on Euphorbia virgata. Plants of Juncus Gerardi were infected 

 by gecidiospores from Cichorium Intybus, and produced the teleutospores 

 oiPucciniaJunci. Pucciniasilvatica was developed on Car ex stenophyUa 

 from the ascidiospores of Taraxacum serotinum. Several other successful 

 cultures are recorded. 



F. J. Pritchard | gives a contribution to the discussion as to the 

 wintering of Fuccinia graminis. He failed to procure the germination 

 of wintered uredospores. He suggests that early infection may be due 

 to the mycelium of the fungus which is often present under the pericarp 

 of diseased seeds, and which develops along with the seedling. He did 

 not consider that any infection came from wild grasses. 



E. AV. Olive § has made a study of the origin of heteroecism in 

 rusts. He concludes that heteroecious forms are the more highly de- 

 veloped, and have originated from simpler lepto- and micro-forms. The 



. * Centralbl. Bakt., sxxii. (1911) pp. 137-58 (2 pis. and 14 figs.). 

 t Ann. Mycol.,x. (191^) pp. 73-6. 



% Phytopathology, i. (1911) pc. 150-4. See also Ann Mycol., x. (1912) pp. 102-3. 

 § Phytopathology, i. (1911) pn. 139-49. 



