SMUT. 



&c., employed are beneficial in other ways, by 

 protecting the seed from vermin, and minister- 



SMUT. 



ing to the future vigour of the plants, steeps 

 generally and very properly adopted. 



are 



* The seed treated with this acid did not vegetate. 



The experiments of Mr. Bevan indicate that 

 lime-water is the most effective of these prepa- 

 rations; and, if this be adopted, it may be pre- 

 pared by mixing 1 pound of fresh lime with 

 3 gallons of boiling water, and the clear liquor 

 then to be poured off and immediately used. 

 In this liquor the wheat should be soaked for 

 12 hours, stirred twice or thrice during the 

 time, and then mixed upon a floor, with the 

 powder made by pouring 3 gallons of boiling 

 water upon 4 pounds of lime. I have had no 

 experience of the effects of lime-water as a 

 preventive of the smut ; but with stale urine, 

 and a solution of common salt, I have wit- 

 nessed numerous and extensive experiments. 

 The results, without exception, were favour- 

 able and nearly similar; and this being the 

 case, a preference is to be given to common 

 salt, as being decidedly the most cleanly and 

 the least disgusting. The mode which I have 

 observed to be the most effective is, to wash 

 the seed with pure water, pouring this off with 

 all the floating grains, and then allowing the 

 seed to soak for 12 hours in a solution of com- 

 mon salt, having a strength or specific gravity 

 sufficient to float a hen's egg. I have no doubt 

 that lime, like common salt, is effectual against 

 the disease, by reason of its powerful action 

 upon the texture of the fungus tribe. Every 

 housekeeper knows how completely mush- 

 rooms dissolve away when sprinkled with salt ; 

 and in experiments I have made upon the 

 Urcgo segetum, I found that the effect of common 

 salt upon this fungus is not less remarkable. 



Mr. Tull, MM. de Lignerolle, Douat, and 

 others, agree in recommending that the seed to 

 be sown upon any farm should be frequently 

 obtained from other soils ; but, however bene- 

 ficial this may be for securing other desired 

 effects, I do not understand how it can prevent 

 the occurrence of smut unless the seed is ob- 

 tained from a crop and a district notably free 

 from the disease. There is little doubt but that 

 the method in which the disease is imparted to 

 the plant is by its root imbibing the extremely 

 minute seeds of the Urcdo along with the mois- 

 ture of the soil. This opinion is confirmed by 

 the observation that the disease is most preva- 

 lent when the winter has been mild and the 

 spring wet ; for, in such seasons, the abundant 

 moisture passing through the soil is most likely 



to convey the seeds to the mouths of the plants' 

 radicle fibres. 



I remember trying some experiments, the 

 full details of which I have accidentally lost, 

 in which I buried some of the Uredo segetum 

 about an inch below the surface of the soil, in 

 a garden pot in which some wheat was grow- 

 ing, supplying those plants, during their after 

 growth, plentifully with water poured upon the 

 surface of the soil. Not one of these plants 

 escaped infection. 



Another garden pot, in which wheat from the 

 same sample was growing, and similarly treated 

 in every respect, but to which moisture was 

 supplied solely by means of the saucer in 

 which it was placed, both pots being sheltered 

 entirely from the rain, produced plants which 

 were not at all infected. Although it is very 

 apparent that the smut is generally imparted 

 to a wheat crop by the agency of the seed 

 sown, yet I am by no means of opinion that 

 this is the only source of infection. I have 

 kept ears of wheat that were covered and de- 

 stroyed by the Uredo during more ^han twelve 

 months in a situation where they experienced 

 the vicissitudes of temperature during all the 

 seasons, unprotected by more than the paper 

 envelope in which they were suspended in an 

 outhouse. Yet when the Uredo that had been 

 thus exposed was mixed with healthy well- 

 washed seed-wheat, this produced diseased 

 plants in a triplicate proportion more numerous 

 than that not so mixed. This experiment de- 

 monstrates that frost and drought, acting in 

 concert with a damp atmosphere, dojiot destroy 

 the vegetating power of the Urcdo's seed. Such 

 being the fact, why may not this seed remain 

 in the soil ready to impart the plague 1 We 

 know that, owing to its extreme lightness, the 

 seed floats buoyantly in the air, and may be 

 carried by winds to distant soils, which in the 

 autumn of the same year, before any extremity 

 of cold has been endured, will have to bear the 

 wheat crop for the following harvest. The 

 opinion that the soil is one source of infection, 

 is sustained by the fact that fields in the vici- 

 nity of the sea are rarely injured, and never 

 extensively, by the ravages of the smut. 

 Such soils are impregnated more than any 

 other with common salt, and the effect of 

 this saline compound upon the Uredo has been 



999 



