Diseases of the Potatoe. 27 



On the same day I put fourteen potatoes whole, and fourteen 

 cut into fifty-six sets, into a deep box, filled with dry mould. 

 The remaining fourteen whole and fourteen cut, I put into 

 another box filled with moist earth, and which was watered 

 from time to time. At the end of three weeks, all the plants? 

 with the exception of five sets, made their appearance. All 

 this time 'the dry box had been kept from moisture. On the 

 21st of July, however, I allowed it to be moistened with 

 heavy rain, and on the ^8th of July, I took up and extracted 

 starch from the whole. Before doing so, however, I weighed 

 the several lots, and what seemed to me curious was, that 

 each lot of the whole potatoes had gained eight ounces ; while 

 each lot of the cut ones had lost six ounces of its weight, and 

 of their number ten did not vegetate. The sprouts from 

 the whole potatoes weighed four ounces, and those from 

 the cut only two ounces. Yet the starch from the twenty- 

 eight cut potatoes weighed but two ounces, and that from the 

 twenty-eight whole potatoes nine ounces, being exactly the 

 produce in starch of half that number, which was made into 

 starch at the commencement of the experiment." 



Loudon, in his Encyclopaedia of Agriculture, says : " The 

 diseases of the potatoe are chiefly the scab, the worm, and 

 the curl. The scab or ulcerated surface of the tubers, has* 

 never been satisfactorily accounted for ; some attributing it 

 to the ammonia of horse dung ; others to alkali ; and some 

 to the use of coal ashes. Change of seed and of ground are 

 the only resources known at present for this malady. The 

 worm and grub both attack the tuber, and the same preven- 

 tive is recommended. 



The same causes which have been assigned to a total or 

 partial failure of the potatoe in numberless instances, and to 

 a most distressing extent in Ireland, have existed since the 

 cultivation of the potatoe commenced, but without the effects 

 deplored, which have only prevailed within a very recent 



