JULY. 141 



schemes that we could try, we could not induce healthy action after- 

 wards, and the plants ultimately were thrown away. Some alarmists, 

 when it first appeared, attributed the potato disease to the use of 

 guano and other artificial manures ; and though I cannot go the 

 length of considering guano the cause, I have little doubt that, used 

 in excess, it is calculated to increase its virulence. With Pelargo- 

 niums I feel convinced that, in addition to the debilitating effects 

 of breeding " in and in," the improper use of highly stimulating 

 manures has been one of the principal causes of the wide-spread 

 mischief; and so long as we continue their use, more especially 

 of guano and other strong ammoniacal manures, so long will the 

 disease continue to spread. 



Of preventive measures, breeding only from perfectly healthy pa- 

 rents in future, and to break up every plant which shews the dis- 

 ease, is the first point. This season I have destroyed among my 

 seedlings at least one hundred plants before they bloomed, fearing 

 that if I allowed them to flower I might be induced to keep them ; 

 and at the present time I have some scores which must " gang the 

 same gate," as I am quite determined to extirpate the disease from 

 my stock of seedlings, if such a thing be possible. The next step 

 will be to pot the seedling plants in pure and simple soils, avoiding 

 strong ammoniacal manures as a perfect bane to success. Of pure 

 and simple soils, I should regard mellow turfy loam, thoroughly ex- 

 posed by frequent turning to the ameliorating influence of air and 

 frost for at the least one entire winter, intermixed with rich fibrous 

 peat, or semi-decomposed leaf-mould, where such can be prepared of 

 the right sort, with sufficient coarse gritty sand and charcoal to secure 

 the porosity of the mass, after the vegetable fibre in the soil has dis- 

 appeared, as the best. Leaf- mould, especially such as we procure 

 about London, is rarely of a healthy description ; for it is composed 

 of leaves of all kinds, frequently intermixed with weeds, the sweep- 

 ings of lawns and walks, and other extraneous matters. It decays 

 more from age than healthy fermentation, and consequently con- 

 tains matters which would be eliminated and thrown off by proper 

 sweating. If good fresh dung from the stables and the dry clean 

 leaves of Oak or Spanish Chestnut could be decomposed toge- 

 ther, they would form a fine manure for mixing for all pot-plants ; 

 but leaf-mould, such as is generally used, is scarcely fit for gar- 

 den purposes. Slowly decomposed, I believe leaf-mould contains 

 a good deal of tanic acid ; for a year or two back a friend of mine 

 destroyed the whole of his cucumbers and mellons by using water 

 which had drained into a tank from a heap of many wagon-loads of 

 leaves ; and the leaf-mould which I used to obtain from Greenwich 

 Park, which was decomposed in holes half filled with water the 

 greater part of the year, was of the very worst description. In using 

 charcoal procure the very best in lumps, and break it yourself; avoid 

 that made from peat, for it is found any thing but suitable for pot- 

 plant cultivation. 



Of remedial measures, of course perfect cleanliness will be of great 

 importance. The glass, the stages, the house, the paths, the pots. 



