PREVENTION OF SMUT. 235 



quotes some of the most eminent naturalists in sup- 

 port of the opinion, that what passes by the different 

 names of smut, dust-brand, and burned corn is a parasit- 

 ical fungus, which preys not only upon the sap, but 

 destroys the very organic structure of the grain and 

 chaff upon which it fixes. Botanists generally dis- 

 tinguish this fungus by the name of urido segeturn. 

 Chymical analysis has shown it to consist, 1st, of 

 about one third of its own weight t)f a green, buty- 

 rous, fetid, and acrid oil: 2d, nearly one fourth of a 

 vegeto-animal substance, perfectly similar to that 

 which comes from putrid gluten : 3d, of a black coal, 

 one fifth of its weight, similar to that which is found 

 in all remnants of putrid organic compounds : 4th, of 

 free phosphoric acid, amounting to scarcely more than 

 .004 of the smut : 5th, of phosphates of ammonia, 

 magnesia, and lime, in the proportion of a few thou- 

 sandths. " The contagion attacks especially the 

 gluten, and precedes, indeed prevents, the formation 

 of starch." It has also been shown by Duhamel, 

 Kirby, and others, that the disease exists in the af- 

 fected plant before the development of the head ; 

 that it is propagated by minute seeds, which attach 

 to the kernel, and which are so light as to float 

 buoyantly in a damp atmosphere ; that the vitality 

 of these seeds is not destroyed by frost; but that 

 they will contaminate seed-grain with which they 

 come in contact after being long in the soil. In 

 early spring, when the plants were but a few inches 

 high, upon carefully opening the hose or blade which 

 covers the ear, M. Duhamel found this erribryo al- 

 ready black and distempered. After quoting the re- 

 sults of many experiments, besides those in the 

 above table, made by Mr. Bevan, Mr. Johnson adds : 

 " The conclusion from these and many other ac- 

 cordant experiments is, that washing the seed is ef- 

 fective in preventing the communication of the dis- 

 ease to the crop. If the washing were frequently 

 repeated, or the cleansing made complete, by pass- 



