DISEASES CAUSED BY FUNGI. 75 



jui'ious. Some of tliesc, as Smut and Bvmt, attack tlie tissues 

 of the seeds, their floral envelopes^ or the receptacle in which 

 the flowers grow, or, in rarer instances, the leaves and stems, 

 converting them into a mass of loathsome, sometimes fetid 

 dust ; others, as Mildew and Rust, attack the leaves and 

 stalks more especially, forming little rusty spots or streaks, 

 and exhausting the plant by the growth of their spores and 

 spawn at its expense. Sometimes they exercise a specific 

 action upon the tissues, and cause the plant to assume vari- 

 ous thickened or distorted forms analogous to those which 

 are produced by the punctures of insects. Some of these, as 

 Bunt, admit of easy extirpation,"^ as the spores will not grow 

 when treated by various chemical substances, and, as they are 

 lighter than water, are in great measure removed by simply 

 washing the seed. The others, as far as is at present known, 

 admit of no remedy, though several nostrums are exten- 

 sively sold under the pretence of preventing their growth. 



There remains another Fungus productive of disease in the 

 grains of rye, barley, wlieat, and many field grasses, under 

 the name of Ergot. The white substance of the seed is con- 

 verted by this Fungus into a firm mass, without any appear- 

 ance of meal, and when the Ergoted grain is sown, it produces 

 a small species of Coi'dlceps (Plate 23, fig. 7), not unlike the 

 species which attack insects. 



* Steeping tlie wheat in solutions of mineral salts, puddling it with qmck- 

 limc stin-ed up in boiling water, and plain washing with water or brine, are 

 amongst the^means employed. The most efficacious, perhaps, is one used in 

 France— viz. steeping the grain in a strong solution of Glauber's salt (sul- 

 phate of soda), and then dusting it with quicklime, the effect of whicli is to coat 

 the seeds with sulphate of lime or g3"psum, and to set free caustic soda for the 

 destruction of the Bunt spores. Where solutions are used, the Bunted grains 

 which have not been broken in threshing are skimmed off, and it is probable 

 from the other practices, where the contents of the unbroken Bunts can scarcely 

 be affected, that those spores of the Bunt only are injurious which are scattered 

 over the Wheat. 



