350 MASSACHUSETTS AGRICULTURE. 



is evident that it might be checked and perhaps nearly eradi- 

 cated by observing the following requirements : 1. Let every 

 diseased potato be burned, boiled, or dissolved in caustic, before 

 it be thrown upon the compost heap or upon the land. 2. Let 

 no field in which potatoes were raised the preceding year, unless 

 they were perfectly sound, be used on the following year for a 

 potato crop. 3. See that no rotten potatoes have, at any time, 

 the least communication with those which are designed for 

 seed, 4. If there be any probability that the seed potatoes 

 have thiis imbibed a taint, let them be washed in the chloride 

 of lime before they are planted, to kill the virus that might 

 otherwise be buried with the tuber, on its surface. 



As the means of ascertaining whether the disease be conta- 

 gious or not, we might institute the following experiments : 

 Let a virgin soil in a field, say of three acres, be ploughed at 

 one time, and divided into three parts, taking care that the soil 

 of the whole field is uniform and equally exposed to light and 

 moisture. Manure one of these acres with a compost contain- 

 ing a li]jeral mixture of diseased potatoes. Let a second be 

 manured with some substance that could have had no possible 

 communication with the virus ; and let the third portion of the 

 field remain without the application of any kind of a fertilizer. 

 Plant each division of the field with sound potatoes, of the 

 same kind and from the same lot, after washing all the seed in 

 some disinfecting fluid. Take pains to cut open every tuber 

 before it is planted, to see that it contains no visible marks of 

 the disease or of its symptoms, and reject all that look sus- 

 picious. 



Watch the result when the crop is taken from the ground. 

 If the potatoes in the first division, which was manured with 

 compost, containing diseased potatoes in a decayed state, bear 

 a crop which soon becomes infected, while those in the other 

 two divisions remain sound, we have incontestible proof that 

 the disease is contagious. But it still remains to be proved 

 that there are not also other ways by which the disease might 

 be engendered. A constant repetition of such experiments 

 continued through a number of years with the same result, 

 would demonstrate that the disease might be averted, by scru- 

 pulously preventing any communication between the planted 



