ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 343 



Fungi. 

 (By A. Lorrain Smith, F.L.S.) 



Biology of Saprolegniese.* — Gaston Bonnier made artificial cultures 

 of Scvprolegnia ThureU in a solution of glucose with a slight addition of 

 citric acid. When grown anaerobically in an atmosphere of hydrogen, 

 all development ceased. In aerobic conditions it grew vigorously, and 

 produced a somewhat complex fermentation. He found, also, that the 

 fungus could live in a medium containing; a mere trace of mineral 

 substances. 



Development of Ascomycetes.f — In following out the development 

 of Boucliera, P. Clausen describes first of all his methods of culture, the 

 appearance of Boucliera at different stages, and the reagents used by him 

 to fix and stain the fungus so as to obtain the best results. He grew 

 the fungus from the spore stage to the ripe fruit on agar with dung 

 solution. No conidial form was produced. At an early stage of growth, 

 short thick lateral branches are formed on the main hyphre, which im- 

 mediately branch again somewhat irregularly. From the same filament, 

 or from one near, arise other branches which wind round those already 

 described. The first formed branch becomes 3-celled — the upper cell 

 is the trichogyne, the one immediately below is the ascogonium. An 

 opening is now visible between the trichogyne and the winding filament, 

 or antheridium, and from the ascogonium the asci begin to grow out. 

 A blunt outgrowth is first formed, which bends over like a crook ; the 

 tip and base are cut off, and the central cell — the upper cell of the bend 

 — forms the ascus. A large nucleus, or sometimes two nuclei, are visible 

 at this stage in the ascus cell. The number of asci arising from one 

 ascogonium could not be accurately determined : there are probably four 

 or five. No difference in development or appearance could be dis- 

 tinguished between the hypha? forming the outer wall of the fruit and 

 those forming the paraphyses ; the latter are septate, and each cell 

 encloses several small nuclei, similar to those of the mycelial cells. 



The author then proceeds to a more detailed description of the cells 

 and their contents. These are multinucleate from the beginning ; the 

 fertile branches are also multinucleate. The ascogonium contains five 

 to six nuclei ; there were fewer in the end cell, the trichogyne, and these 

 degenerate at the time when fusion takes place between the trichogyne 

 and the antheridium. No opening was seen between trichogyne and 

 ascogonium, but the nuclei of the latter increase to double the number, 

 no nuclei being left in the antheridium, and the author concludes that 

 the antheridial nuclei have passed over to the ascogonium. The nuclei 

 in the ascogonium then fuse in pairs, the resulting nuclei being 

 distinctly larger. When the ascogenous hyphas grow out from the 

 ascogonium they are at first bi-nucleate, then after bending over the 

 basal and terminal cells are both seen to contain one nucleus only, the 

 central cell — the young ascus — is bi-nucleate. These two nuclei ulti- 

 mately fuse, and the uninucleate stage of the ascus persists for some time 



* Couiptea Rend us, cxl. (190.')) pp. 454-5. 

 t Bot. Zeit , lxiii. (1905) pp. 1-28 (3 pis.). 



