ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 341 



down." The conidia of the Erysiphe fungus were induced to grow on 

 plants otherwise immune to their attacks by previously injuring the 

 leaves. The fungus growth thus produced could then readily infect 

 an uninjured surface of the same host. Plants are subject to many 

 accidents, and Salmon holds that by the aid of such injury, a fungus 

 may get hold of a host otherwise safe from attack, and this may account 

 for sudden outbreaks of disease. It may also explain the nature of 

 wound fungi, such as Nectria, etc., which infect the host only through 

 wounds. 



Cultural Experiments with the Barley Mildew, Erysiphe gra- 

 minis D.C.* — E. S. Salmon had already demonstrated the existence of 

 biologic forms of this fungus with species of Bromus as host-plants. 

 He has made a further series of cultures on Hordeum, to find whether 

 any species or variety of barley of economic importance would show a 

 difference as regards susceptibility to the attacks of the parasite. He 

 chronicles in several instances cases of what he terms sub-infection, 

 when one out of many inoculation experiments would alone be suc- 

 cessful, and cases where a very modified infection took place. The 

 latter instance he explains by the fact that several haustoria have pene- 

 trated one epidermal host-cell, and the enzyme present in the cell failed 

 to kill them all, so that the fungus succeeded in producing a modified 

 growth. As a result of his observations he judges " that immunity 

 and susceptibility are due to constitutional (physiological) peculiarities 

 and not to any structural ones." He concludes that some varieties 

 are, under natural conditions, more resistant to attacks of the disease 

 than others. Detailed tables are given of the various experiments. 

 He also tried the effect of copper sulphate as a fungicide when applied 

 to the roots of the cereals. He found that even when solutions strong 

 enough to distort the plants were applied to the soil, the leaf-cells still 

 remained susceptible to the fungus. When he grew the seedlings in a 

 water solution with the same strength of copper introduced as that with 

 which he had watered the soil, they all died off. The control cultures 

 in pots of soil watered by a copper solution grew into robust plants, 

 each with a powdery patch of mildew. 



Forms of Saccharomyces.t — Alb. Klocker publishes a new species, 

 Sacch. Saturn us, the spores of which are distinguished by a distinct 

 band round the centre, and by a somewhat citron shape. He was able 

 to grow them on plaster blocks and by various other methods. The 

 new yeast ferments dextrose, levulose and raffinose ; it inverts saccha- 

 rose and then ferments the inverted sugar. Along with the fermentation 

 an ether is produced. The species was found on soil from the 

 Himalayas. One somewhat similar has been noted in Danish and 

 Italian soil. 



Saccharomycopsis.J — This new genus of Yeasts was isolated from 

 soil collected near the St. Gothard Pass by H. Schionning. It is 



* Ann. Mycol. ii. (1904) pp. 70-99. 



+ Comptes Rendns, Lab. Carlsberg, 190o, pp. 84-91 (6 pis.). 



t Tom. cit., pp. 101-25 (5 figs.). 



