48 



SCIENCE 



[N. S. Vol. L. No. 12S 



much that is new and is a valuable contri- 

 bution to the difficult subject of the interrela- 

 tionship of several Palaeozoic plants exhibiting 

 remarkable complex anatomical features. 



A. C. Seward 

 University of Cambridge 



SPECIAL ARTICLES 



THE BLACK CHAFF OF WHEAT 



The continued prevalence of black chaff of 

 wheat in the United States makes it desirable 

 to have a Latin-scientific name for the bac- 

 terial organism causing it. This organism 

 resembles Bacterium translucens (see Journal 

 of Agricultural Research, Vol. XL, p. 625, 

 1917), cause of the bacterial blight of barley. 

 In cross inoculations on the leaves of seedling 

 plants the barley organism on wheat has 

 proved either non-infectious or has produced 

 small non-typical lesions. On the other hand, 

 inoculation experiments have shown that the 

 wheat organism is practically as pathogenic 

 on barley as it is on wheat and the lesions so 

 produced on barley are indistinguishable from 

 those produced by the barley organism itself. 

 There also appear to be minor cultural differ- 

 ences. It is suggested, therefore, that for the 

 present, at least, the wheat organism be dis- 

 tinguished as Bacterium translucens var. un- 

 dulosum with, in general, the characteristics 

 already given for the species : 



Var. undulosimi nov. var., cause of the black 

 chaff disease of wheat, produces yellow or 

 translucent stripes on leaves, water-soaked or 

 black stripes on culms, and longitudinal, 

 more or less sunken, dark stripes or spots on 

 the glumes. In moist weather the bacteria 

 often ooze to the surface of the diseased siwts 

 or stripes as tiny beads or drops, drying yel- 

 lowish. From sections of diseased leaves or 

 glumes mounted in water they ooze in enorm- 

 ous ntimbers (like smoke out of a chimney) 

 making the fluid cloudy. This organism at- 

 tacks also the kernels, especially at the base 

 causing them to be shrunken and honey- 

 combed with babterial pockets, but even when 

 the kernels are not attacked their surface is 

 liable to be infected from the diseased glumes. 

 "When the disease appears early and is severe 



the heads are dwarfed. Surface colonies on 

 thin-sown agar plates are circular, pale yellow, 

 smooth (like polished glass) and structure- 

 less on the surface, usually homogeneous also 

 by direct transmitted light, but by oblique 

 transmitted light (half-light) the interior is 

 seen to be full of minute waves or interblend- 

 ing striations which persist, and which are 

 best seen with a hand lens. It can be dis- 

 tinguished easily and quickly from accom- 

 panying non-parasitic yellow forms by this 

 character alone. Slime copious and very pale 

 yellow on potato agar; on whey agar very 

 copious and bright chrome yellow — slime on 

 this medimn deeper yellow and less fluid than 

 that of the barley organism. 



Infections have been obtained rex)eatedly on 

 wheat leaves and glumes. The disease is 

 transmitted to young seedlings by way of the 

 wheat kernels. It occurs in all the wheat 

 states of the Middle "West. 



For earlier notes consult Science, 'N. S., 

 Vol. XLIV., ISTo. 1134, p. 432, 1916, the Jour- 

 nal of Agricultural Research, Vol. X., No. 1, 

 1917, and the Plant Disease Bulletin (issued 

 by The Plant Disease Survey, Bureau of Plant 

 Industry, U. S. Department of Agriculture), 

 Vol. I., ISTo. 2, 1917, and Vol. II., No. 6, 1918. 



Erwin p. Smith, 

 L. E. Jones, 

 C. S. Eeddy 



THE BUFFALO MEETING OF THE 

 AMERICAN CHEMICAL SO- 

 CIETY. V 



The rapid determination of titanium, in titanifer- 

 ous iron ores: John Waddell. The ore is fused 

 in a silver, copper or iron crucible withi sodium 

 peroxide, for about ten minutes. The crucible 

 with the fused mass is brought into a beaker with 

 water, and the disintegrated material dissolved in 

 sulphuric acid. Tartaric acid is added to keep the 

 titanium in solution. Sulphuretted hydrogen is 

 passed through the solution. If a copper or silver 

 crucible has been used, the precipitated sulphide 

 is filtered off, and to the filtrate, ammonia is added 

 and more sulphuretted hydrogen is passed. To the 

 filtrate from the iron sulphide, sulphuric acid is 

 added and the solution is boUed to drive off the 



