Quarterly Journal of' Agriculture. 175 



Europe." The only checks likely to be effectual in England are general 

 education enforced by law, doing away the application of the poor rate to 

 able-bodied labourers, and a positive prevention of marriage in both sexes 

 of the lowest class till a certain age, or till the concurrence of certain cir- 

 cumstances. 



On Mixtures in the Air which occasion Disease and Death in Platits. — 

 M. Marcet proved by experiment that plants were poisoned by water hold- 

 ing oxide of arsenic in solution, and by a few grains of arsenic introduced in 

 a cut. Opium, hemlock, foxglove, and oxalic acid, absorbed by plants, also 

 killed them. D. Martin, Esq., found cast-iron tallies poisoned the soil about 

 the roots of his pinks and carnations ; and the trees and plants in the towns 

 of Britain, where the atmosphere is more or less impregnated with coal 

 smoke, are never so green and luxuriant as those in the country, or those 

 in the towns on the Continent where wood is used as fuel. The sulphurous 

 acid gas is exceedingly deleterious to vegetables, even when there is so 

 small a quantity in the atmosphere, as to be hardly or not at all discoverable 

 by the smell. " In opening up to the agriculturist these sources of death 

 and disease to vegetation, do we not enable him to look upon his soils and 

 his crops with an enlightened eye ? " 



Remai~ks upon a supposed Law of Vegetable Life, limiting the Duration of 

 Plants obtained hy Cuttings to the Natural Term of Life of the Stock luhence 

 they were taken. By the Rev. Dr. Fleming, of Flisk. — This is a most va- 

 luable paper. When Marshal, in his Rural Economy of Gloucestershire, 

 remarked that " engrafted fruits are not permanent, they continue but for 

 a time," he probably did not anticipate that he was announcing a conjecture 

 destined to become an article of faith, under different forms, among intelli- 

 gent agricultural and horticultural writers. Mr. Knight embraced the opi- 

 nion of Marshal, and, in his Treatise on the Culture of the Apple and Pear, 

 gave it as his opinion, that " the continuance of every variety appears to 

 be confined to a certain period, during the early part of which only it can 

 be propagated with advantage to the planter." Mr. Bucknall expresses 

 himself more plainly on the subject, in the Transactions of the Society for 

 the Encouragement of Arts. " When the Jlrst stock shall, by mere dint of 

 old age, fall into actual decay, a nihility oi vegetation, the descendants, hosv- 

 ever young, or in whatever situation they may be, will gradually decline ; 

 and from that time it would become imprudent, in point of profit, to at- 

 tempt propagating that variety from any of them." There was now only 

 wanting the authority of a botanist, to give sanction to the opinion, that 

 plants obtained by cuttings did not possess an individual vitality, but were 

 merely dependent extensions, sympathising with the frailties of the stock 

 from which they were taken, and incapable of outliving its dissolution. Sir 

 James Edward Smith, the late lamented President of the Linnean Society, 

 considered it as established, that " propagation by seeds is the only true 

 reproduction of plants." With such authorities, this supposed law of ve- 

 getable life was eagerly and generally acquiesced in, and considered as ac- 

 counting for the decay of certain productions of the orchard, the garden, 

 and the fields. 



Dr. Fleming refuted the opinion in his Philosophy of Zoology (vol. i. p. 

 4'26.), published some years ago, and here adds a few additional facts. These 

 are, that cuttings from the scarlet lychnis and wallflower may be prolonged, 

 as plants, for an unlimited length of time ; that the leaf of a potato may 

 be made to outlive the stem ; that oats and beans were kept ahve by him 

 for four years, by preventing them from producing flowering stems ; that 

 the osier, gooseberry, poplar, &c , have been propagated by extension for 

 ages, and that the plants still perform their respective functions ; in short, 

 as we have already shown (Vol. II. p. 411.), that a bud, which ever way made 

 to throw out leaves and roots, is essentially as good as a seed. 



