212 PLANT DISEASES 



along with the typical form. In this hidden form the 

 chaff is not destroyed, and the spore-mass is concealed in 

 the grain. 



Brefeld has proved that inoculation can only be effected 

 when the oat plant is quite in the seedling stage, immedi- 

 ately after germination. Smut spores adhering to the oat 

 seed germinate at this period, produce a promycelium, 

 which bears secondary spores, and these latter inoculate 

 the young oat plant, the germ-tubes entering its delicate 

 tissues, and grow along with the oat plant until its flower 

 is produced, when the fungus produces its spores under 

 the form of 'smut.' 



PREVENTIVE MEANS. The hot-water method is effective, 

 as is also steeping the seed in a solution of potassium 

 sulphide 1| pounds in 25 gallons of water for twenty- 

 four hours, stirring thoroughly at intervals. A wooden 

 vessel should be used. 



It has been definitely proved that by using either of 

 the above methods, a much greater increase in the yield 

 is obtained than would result by merely replacing the 

 smutted by sound grain. 



Close has recently conducted an extensive series of 

 experiments, proving that sprinkling the seed grain with 

 a one per cent, solution of either lysol or formalin entirely 

 prevented the smut. 



Brefeld, Nachrichten aus dem Klub der Landzvirfhen zu 

 Berlin, 1888, No. 220 et seq. 



Jensen,y<?#r. Roy. Agric. Soc. England, vol. xxiv. pt. 2, 

 1888. 



Rostrup, Nogle Undersogelser angaande Ustilago Carbo, 

 1890. 



