280 MASSACHUSETTS AGRICULTURE. 



ESSEX. 



PLAN FOR INVESTIGATING THE POTATO DISEASE. 



13 Y WILSON FLAGG. 



It is about fifteen years since the first general appearance of 

 the potato disease. During this time the whole civilized world 

 has been investigating its causes, its nature and its remedy. 

 This disease is marked on its first approach by a slight discol- 

 oration of the surface of the tuber, gradually penetrating its 

 substance, and causing a hardness of the pulp most apparent 

 after the potato is cooked. This hardness bears some resem- 

 blance to that of a tuber of the preceding year's growth, which 

 is sometimes found in the hill among the new potatoes. No 

 amount of boiling will soften either the one or the other; 

 though they will yield to a greater degree of heat than 212° 

 in an oven, and become softened. Throughout the diseased 

 substance there is a brownish or rusty hue, sometimes in irregu- 

 lar streaks, and sometimes uniformly blended with the mass. 

 The final stage of the disease is a softening of the part, which 

 seems to be identical with its corruption, when it is almost 

 black. Such are the superficial appearances of the disease ; 

 its nature has not been yet ascertained. Several theories have 

 been put forth to explain it ; but they are all unsatisfactory to 

 the reason and common sense of impartial inquirers. 



Among the theories which have been advanced to explain the 

 nature and causes of the disease, four have attracted public 

 attention and have been warmly advocated by their respective 

 authors. The fungus theory, which I will name first, supposes 

 that the rot is caused by inoculation with the spori of a certain 

 species of fungus, which, like a true parasite, penetrates the 

 substance of the tuber, and thrives upon its nutritious proper- 

 ties. This fungus has been supposed to resemble the red rust 

 that attacks the leaf and stem of Indian corn and other cereal 

 plants. It is now believed to be the consequence, not the 

 cause of the disease, being always developed subsequently to 

 the gangrene of the tuber. 



