Cultivation of Arable Land. Wheat. Blaft and Smut in. -S3 



infers, the action of other plants, a corrupted ftatc of the vegetable fluids, or 

 fome peculiar defect in the vegetative proccfs of the plants, it is probable the 

 beil mode of preventing or removing it will- be the expofure of the plants as 

 much as pofiible to the influence of the air, by fovving the grain with larger 

 fpaces, or thinning them out, when too thick and clofe, by the hoe. in the later 

 .fpring months, when the ftate of the crop is fully afcertained. That fuch me 

 thods may be beneficial, is clearly mewn by the general obfervation, that hilly 

 diftricts are much lefs expofed to the difeafe than fuch as are low, flat, and 

 confined. 



The blajl is an affection of vegetables that proceeds from -lightning, or the 

 intenfc action of the fun, when the plants are in a flate of considerable aptitude 

 for the action of ftimuli. It is the mod common in hot climates ; but Dr. Dar 

 win, from having found that extenfive wood-cutters often find trees cracked on 

 being fawn through, fuggefts lightning as a more frequent caufe of the difeafe 

 in this country than is commonly fuppofed. The effects of thefe caufes on 

 wheat crops have been noticed by Tull, and defcribed as occurring in blackifh 

 patches indifferent parts of the fields. As the vital power of the plants is 

 moftly, in thefe cafes, either completely exhaufted by the great and fudden 

 operation of fuch fthmili, or their vafcular fyftcm deftroyed by their expanlive 

 action, no remedy can be of any great utility.* 



The ufilagO) orfwuf&amp;gt; is another vegetable difeafe to which wheat and other 

 grain crops are often expofed, and in which a fort of black meal is produced in 

 the place of feed. It has been afcribed to many different caufes by writers on 

 agriculture. It is remarked in the Memoirs of the Bath Agricultural Society, 

 that this is a difeafe that only occurs when the weather is wet during the period 

 of flowering, in which the anthers may burfl, and the farina be warned away. 

 The difeafe is there fuppofed not to be produced by any infectious fubfrance, or 

 the ova of infects that may adhere to the grain, as fmutty ears and found ones 

 were found proceeding from the fame root, and, in fome inftances, both fmutty 

 and found grains to be contained in the fame ear; fome of the corns having 

 even one end fmutty and the other found. It is therefore fuppofed to arife in 

 confequence of the want of due impregnation, from the farina fecundans being 

 faulty, and that putrefaction takes place on the death of the corn. This opi 

 nion is fupported by the experiments of Spallanzani, who difcovered that the 



* Darwin s Pbytologia, p. 332* 



i 



VOL. n. F 



