No. 105.] 343 



other known disease, and the mode of cultivation recommended in 

 this paper to preserve the potato from it, being directed to the im- 

 provement of its growth and physical properties, and applicable to 

 the successful cultivation of the potato under all circumstances, we 

 shall limit our observations to this subject alone. 



The " rot in potatoes.''^ 



The disease known by this name, has occurred at various periods, 

 under various names, during the last half century, on the European 

 continent, and on the British isles ; assuming latterly an epidemic 

 character, and extending its ravages over large districts of country. 

 As it has appeared in our own country, it may be described in four 

 stages, by diagnostic marks upon the tuber of the plant. 



Incipient. 



In the first or incipient stage of the disease, the potato appears to 

 the eye sound and handles well ; but on cutting it open, there is a 

 crispness perceptible, caused by the fibres being in a state of contrac- 

 tion, and a milkiness of the juice, peculiar to this disease. After 

 cooking, the potato remains watery, and has a rank flavor, that 

 leaves a scratchy sensation on the fauces, and if eaten even sparingly, 

 produces soporific effects on the senses. 



Fementation. 



In the second, or fermentative stage, the potato has sometimes 

 specks or blotches on the cuticle, that feels soft under pressure, but 

 more frequently the external surface presents no diagnostic mark ; on 

 cutting open the potatoe, it presents a yellowish, brown, or black 

 border of demarkation between the cuticle and that part of the pota- 

 to apparently soiind, or in the incipient state. This border varies 

 in depth from a line to one-third or more of the thickness of the po- 

 tato. In this stage the potato has undergone a chemical change, 

 that has developed poisonous principles, and is dangerous as food for 

 Inan or beast. When boiled they emit a fetid smell. In this stage 

 of the disease, if the potato is left in the ground, or harvested, and 

 placed in masses, in a damp and warm place, the disease progresses 

 rapidly into the 



