POTATO ROT. 663 



unless the seedlings have been, at all stages, completely sepa- 

 rated from the old varieties, and unless they have been derived 

 from healthy plants, or are separated, by a sufRcient number of 

 removes, from their unhealthy progenitors. 



I come now to the method which t!ie above views would 

 lead us to consider the only certain one, with a view to the 

 final extirpation of the disease ; and it is one requiring the 

 means at the command of the government of a state, or some 

 public body or institntion, devoted to agricultural improvement. 

 It is to cultivate the potato from the ball, for several genera- 

 tions continuously, until the hereditary taint is removed, and 

 then to distribute the healthy tubers to such agriculturists as 

 will pledge themselves to abandon entirely the culture of the 

 present exhausted and diseased varieties. 



To succeed in the experiment, it should be conducted on a 

 well managed model farm, or horticultural garden, from which 

 the culture of the old varieties should be entirely excluded, 

 and seed should be obtained from the balls of the most healthy 

 potatoes. 



The ground should be light and dry, and manured with a 

 mixture of old compost, lime, gypsum, and wood ashes. 



The seedlings should be carefully tended and kept very 

 clean from weeds, and any plant in which the first signs of 

 blight appears, should be at once destroyed. 



A part of the seedlings should be carefully covered, and al- 

 lowed to remain in the ground all winter. The remainder 

 should be carefully packed in dry sand, in a cool cellar, keep- 

 ing the various sorts separate. 



In the second year, the same precautions should be used as 

 to the culture of the best varieties obtained in the first year, and 

 some of the plants should have the soil washed away from 

 their roots, and the young tubers picked off, in order to ensure 

 the production of balls. After picking off the tubers, the plants 

 should be carefully earthed up again. 



The seed from the balls of the second year, should be sown 

 in the third year, and the whole process repeated, as before. 

 The tubers obtained from the first sowing, should not be dis- 

 tributed as seed potatoes ; but those from the second sowing 



