No. 133.] 319 



As to the posibility of shielding the potato from the malady 

 we must he permitted to doubt, and for the following reasons : 



, We received, in 1849, from the gardens of Germanji, another 

 species of solanum, which had been brought from Mexico. M. 

 Kloztsch hastened to decorate it with the title of solanum utile, 

 (the useful potato,) and the following year the Botanic Gazette 

 informs tliat in the garden of the Institute of Eldena this species 

 had the malady. 



The solanum demissum, introduced from Mexico into the gar- 

 den of the Horticultural Society of London, was also attacked by 

 the malady, even in the first year. It is true that another plant 

 of the same lot, reported by Dr. Lindley as being a solanum ver- 

 rucosum, remained sound. We infer that this sort is really more 

 robust ; our experience of the two last years make us think so. 



Unfortunately, when we cultivate the potato for the market, we 

 feel obliged to manure well, in order to get as large a crop as 'pos- 

 sible ; so the tubers augment in size, but the phisological harmony 

 of the species is destroyed. An excessive production of starch in 

 any plant, like a great increase of fat in an animal, becomes either 

 a direct cause of disease, or, at least,an indirect cause of debility, 

 of certain organs, and the disease of the potato seems to prove 

 what I advance. The malady prevailing at the same moment in 

 diflerent climates, it is difficult to believe that it is owing to any 

 local causes or to external physical causes. The humid climate 

 of Ireland bears no similarity to those of Spain or Russia ; and 

 the climate of Switzerland is entirely opposite to that of Holland ; 

 but the malady declares itself everywhere within the last six 

 years. For a disease so general I am forced to find some general 

 cause, independent of climate ; a cause either direct or indirect, 

 no matter which, provided it be general. 



And here is one of the causes : The solanum tuberosum (all 

 travelers say) grows in sterile lands, often among the sands and 

 pebbles of a sea shore. We put it into fertile soils and force it 

 with manure. For fifty years past we have diminished oar fal- 

 lows and increased our manuring. This regimen is so contrary 

 to the primative condition of the potato that it cannot be without 



