ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 219 



this disease. The first attack is due to the ascospores of the fungus. 

 'The perithecia are developed on vegetable remains on the ground, and 

 the spores are expelled during the first rainy season. The wind carries 

 them to the vines, and pycnidia are formed. The spores of the pycnidia 

 first formed are washed over the branches by subsequent rains, and the 

 spread of the fungus is secured. The precise dates of attack and further 

 spread of the disease are thus ascertained, and measures can be more 

 •easily taken to check the mischief. 



Mycological Notes.* — P. Magnus gives here the diagnosis of a 

 rather unusual species of Erysiphe found on Asteriscus aquaticus. It is 

 -characterised by the somewhat flat apothecia, which are held so firmly to 

 ■the leaf by the appendages that the surface of the leaf becomes depressed 

 by the pressure of the fungus. Magnus also publishes notes on some 

 Hyphomycetes ; Ovidaria pus ilia should be called 0. aplospora, and 

 Helminthosporium Diedickei should be Brachysporium Crepini. 



Further Cultural Experiments with Biologic forms of the 

 Erysiphaceae.f — In a recent paper, E. S. Salmon described methods 

 ■of culture in which he wounded, or otherwise injured, a host plant 

 hitherto immune to the fungus, and thus rendered it liable to infection. 

 For such a case he proposes the terms xenoparasite and xenoparasitism. 

 In the case of the specialised fungus on its proper host under normal 

 -conditions, he uses the terms cccoparasite and mcoparasitism . 



He found that though he could, by wounding or weakening the 

 host plant, induce a "strange " form to grow on it, yet, in the following 

 generation, the spores so produced refused to germinate on the same 

 host if it were in a healthy condition, while they germinated readily on 

 the host on which the form normally grew. The injuries that rendered 

 the plant liable to infection were mechanical, by cuts or bruises, or they 

 were caused by interference with the normal functions of the cell by 

 the application of alcohol, ether, or heat. A detailed account of the 

 various experiments is given. 



Vitality of Yeast in Varying Conditions.! — W. Henneberg worked 

 with pure cultures of yeast, of which he tested the vitality under the 

 "varying influences of moisture, temperature, illumination, etc. He 

 found that the different races of yeast exhibited different properties, 

 some having more power of resistance than others. A series of 

 researches was directed to the influence exerted by foreign organisms, 

 moulds, bacilli, etc., in the yeast cultures. Some of these gave off very 

 strong odours ; he did not find, however, that they were directly 

 injurious to the growth of the yeast, except in so far as they used up 

 the nourishment, and so impoverished the culture medium. 



Nuclear Fusion in Yeast Spores.§— Gaston Bonnier notes the re- 

 sults arrived at by various workers on this subject, and re-examines a 

 number of cases already experimented on. In Saccharomyc&s Mellacei, 



* Hedwigia, xliv. (1904) pp. 17-18. 



+ Ann. Hot., xix. (1905) pp. 125-48. 



t Centralbl. Bakt., xiii. (1904) pp. 641-5. 



§ Comptes Rendus, cxxxix. (1904) pp. 988-90. 



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