NOTES AND ABSTRACTS. 



837 



S. uniflora, the other cultivated species, comes from Northern 

 Japan, and the finding of this plant in 1868 led to the rediscovery of 

 the first-named species in North Carolina. S. uniflora is dwarf er than 

 the first, with leaves smaller and more obtuse, and has pale pink petals 

 crimped and veined with white. The llowers are more widely expanded 

 and not of the nodding or hooded character of S. galacifolia. S. u. 

 grandi flora is white suffused with pink. The Shortias respond to shelter 

 from hot sun, and are best grown in equal parts of peat, sand, and 

 leaf mould to which a little loam has been added. Natives of the 

 woods, it is probable that with freer supplies of root moisture in more 

 open positions they would succeed well and give enhanced leaf-colouring. 



H. R. D. 



Sideroeapsa Treubii^ a New and Widely Distributed Iron 



Bacterium. By D. Hans Mohsch {A?in. Jard. Bot. Buit. 3rd supp. 

 1st part, 1910, pp. 29-34 ; with one plate). — This forms an interesting 

 addition to the small group of bacteria which possess the power of 

 oxidising the ferrous carbonate occurring in the water in which the 

 organisms live to ferric hydroxide, which appears as a brown deposit 

 in the mucilage sheaths or membranes of the bacteria. The brown 

 layers covering the submerged parts of many water plants (e.g. 

 Elodea, Nymphaea, Salvinia, &c.) has been often observed, but its 

 bacterial origin has only now been demonstrated by Molisch. By 

 means of Schiff's aldehyde reagent Molisch was enabled to render 

 visible the bacteria lying embedded in the brown mucilage. He names 

 this bacterium Sideroeapsa Treuhii. — R. B. 



Silver-leaf Disease, Fruit Trees. By the Duke of Bedford, 



K.G., and Spencer U. Pickering, F.E.S. {Wohurn, Twelfth Report, 

 1910, pp. 1-34). — This is an account of experiments on this disease in 

 continuation of the results up to that date given in the Sixth Eeport, 

 1906. The authors state that the results described put it beyond doubt 

 that it is caused by a fungus known as Stereum purpurcum, the inocula- 

 tion of a tree with a piece of the fungus nearly always producing silver- 

 leaf, whilst neighbouring trees not thus inoculated remain quite healthy, 

 and trees which have died, either partially or entirely, under an attack, 

 often develop Stereum on the dead wood, no single instance being on 

 record of the appearance of this fungus on a tree which has been known 

 to have shown no signs of silver-leaf while alive (p. 2). 



The fungus itself forms flat roundish disks on the bark of the dead 

 tree, about two inches or more in diameter, of a purple or pinkish 

 colour, though sometimes nearly white. For the purpose of inoculation 

 it is only necessary to insert a small portion of the fungus about twice 

 the size of a pin's head in a cut made in the bark, a week or two after 

 which, when a tree is in active growth, there is a gradual appearance 

 of silvering of the leaves, the whole tree possibly becoming seriously 

 affected after four or five weeks (p. 2). 



The outward manifestation of the disease is held to be due to a 

 poison formed during the growth of the fungal threads, as the mycelium 



