296 PRINCIPLES OF GAPvDENIKG. [CH. VIII, 



the decaying part when it first appears, and appljdng 

 to the wound some finely powdered charcoal, will effect 

 a cure if the disease has not penetrated too deeply, 

 yet it mil he liahle to return immediately if a less 

 forcing mode of culture he not adopted. No auricula 

 mil suffer from this disease if it he shifted annually, 

 and the tap-root at the time of moving be shortened, 

 a thorough system of draining being adopted, either 

 by using one of the pots suggested in a previous part 

 of this work, or by having the pot used one-fourth 

 filled with pebbles ; and excessive damp during the 

 winter being prevented by proper shelter. 



Parsley grown in a poor soil is also liable to canker 

 in the winter. Mr. Barnes says he never found any 

 application w^ich eradicated this disease so effectu- 

 ally as a mixture in equal parts of soot and slacked 

 lime sown over the plants. The cure is complete in 

 a few days, and the vigour of the plants restored, 

 indicating that this species of ulceration, like that 

 which is found in the dwellings of the poor, arises 

 from deficient nourishment. 



The spot, as it is technically termed, occurring on 

 the leaves of the jwlargoniiim, is a dry gangrene, 

 occasioned by an irregularity in the supply of 

 moisture, and vicissitudes of temperature, but espe- 

 cially if one of the extremes is much below the 

 degree of heat most favourable to the healthy growth 

 of that plant. The reason of this is very obvious. 



