moffy foils; while, on the contrary, the curl has lately begun to appear,

I 33

but afterwards become curled(b). On this paffage Mr. Somerville remarks,

A piece of ground(deep loam) was well manured with lime, and planted with potatoes; when the plants appeared above ground, nearly three-fourths of them were curled; while at the ſame time a few drills, immediately adjoining, which had got no lime upon the ſoil, and planted with the ſame ſced, were entirely free from the diſtemper. This circumſtance at- tracted notice, and the ſame experiment was repeated next year, with the ſame reſult. Since that time the Author of the preſent Memoir has paid particular attention to thoſe ſituations in which the curl is moft frequent, and he has uniformly found it to prevail moſt in the diſtricts where much lime or aſh-dung is uſed. He has alſo obſerved, that in thoſe Paes where the lime-huſbandry is but partially practiſed, ſuch as the

ills and uplands, ſearce any ſuch thing as the curl is known. There is one circumſtance in theſe upland ſituations that may operate as a preventative to this diſeaſe; that is, the nature of the ſoil, which is for the moſt part moſſy. This idea gains confſiderable ſtrength from obſerving the practice of the Lancaſhire planters, ſome of whom fſend their favourite kinds to the moſſy grounds to recover, after they have caught the diſtemper. The author of the W. Lothian Survey, who in the courſe of that work has diſplayed much learning and ingenuity, takes notice of the circumſtance of po- tatoes not being ſubject to the curl in the hilly and higher grounds. His ex- preſſion is(for we uſe his own words)„It is ſomewhat fingular that this *o diſtemper(the curl) is unknown in the higher diſtrict of the county, at “ an altitude of 400 feet above the level of the ſea.“ He goes on to reaſon 7 upon the probable cauſe of this difference, and ſeems to aſcribe it to the b froſt ſetting in early in the ſeaſon in theſe elevated ſituations, and deſtroy- ing the Haulm of ibe potatoe before it is completely ripe. The inference he draws from thence is certainly a wrong one; for he ſeems to imagine, that in order to raiſe the beſt ſeod-potatoes, they ought to be taken up before they are ripe. Experience, however, contradièts this theory; for it is found that the more completely the bulbs or ſeeds of any plant are matured, the more perfect and productive will they be when they are put into the earth as ſeed. It is evident that the author has aſcribed that to altitude which is entirely owing to the nature of the ſoil; as it is now known, that, even in the loweſt fituations, potatoes do not curl upon

even in the moſt elevated fituations, where the lands are in good heart,

and have been much manured with lime, or coal, or wood-aſhes(c). „Great attention is paid in Lancaſhire to changing the ſeed, to prevent this

diſtemper: a change from moſs-land, and vice verſa, is generally ſufficient 7⁴).

—

5) Weſt Lothian, p. 81. Ic) Ms. Papers of the Board. ſd, Lancaſter, p. 80.