750 SUMMARY OF CURRENT RESEARCHES RELATING TO 



that the cells varied with the host, when the Puccinia occurred on several 

 different species. 



Clamp-Connections and Fusion in the Uredineas.* — W. Voss lias 

 undertaken to supply the gap in our knowledge as to the occurrence of 

 cell-fusions in the Uredineae, many examples having been already noted 

 in the Ascomycetes and Basidiomycetes. He treated the sections of the 

 leaf and parasite with a solution of 1 p.c. osmic acid for about 10 minutes, 

 which hardened and slightly darkened the fungal hyphas ; afterwards he 

 examined them in chloral hydrate. He found numerous examples of 

 cell-fusion, and also clamp-connections in all the species of Uredinea> 

 that were examined. The unfinished clamp-wall always terminated in 

 a slight swelling, and he found further that the completed wall showed 

 pits allowing the continuation of the protoplasm. Clamp-connections 

 have only been detected in the Basidiomycetes and the most highly 

 developed Ascomycetes ; that is, in forms that express a high stage of 

 development. They must therefore be a property of forms with a long 

 evolutionary history, and Voss concludes from this that the Uredineae 

 branched off from the main fungus stem at an early stage and have 

 reached their present form after a long course of development. 



Taxonomic and Cytological Notes on Botryosporium pulchellum.t 

 This fungus has been described under a variety of names. Bene Maire 

 discusses these and finally leaves it as B. longibrachiatum (Oud.) 

 B. Maire. He takes occasion to give the results of his examination of 

 the plant when first observed by him, especially with reference to the 

 formation and function of the metachromatic corpuscles. The plant 

 consists of an axis rising from the creeping filaments and furnished with 

 lateral branchlets which bear heads of spores. The cells of the develop- 

 ing axis and branchlets are filled with a dense cytoplasm with numerous 

 nuclei difficult to stain. No metachromatic corpuscles were present. 

 At a later stage the nuclei are more easily coloured, and division by 

 mitosis was noted in the heads of the branches that bear the conidia. 

 They were too minute to allow details to be followed. At the stage of 

 conidia formation, metachromatic granulations were present, and crystals 

 which later also became metachromatic granulations. As the conidia form, 

 the cytoplasma, the metachromatic granulations and finally a nucleus pass 

 in. The conidium then drops off and the branchlets are seen to contain 

 only cytoplasm and a few nuclei which degenerate. There are no 

 metachromatic corpuscles. They are, however, very numerous in the 

 cells of the main axis at the base of the branchlets. These observations 

 made by Maire incline him to adopt Guilliermond's theory that these 

 bodies are secretions of reserve material having the same physiological 

 significance as starch-grains, crystals, &c. 



Nuclear Behaviour and Spore-Formation in Hydnangeum car- 

 neum.J — -Van Bambeke gives a preliminary account of his observa- 

 tions on the cytology of this form, and criticises the work of Istvanffi, 

 Petri, and Buhland. The subhymenial cells show constantly two nuclei 



* Ber. DeutBch. Bot. Ges., xxi. (1903) pp. 366-71 (1 pi.). 



t Ann. Mycol., i. (1903) pp. 335-40. 



X Bull. Gl. Sci. Acad. Roy. Belg., 1903, pp. 515-20. 



