I. AGRICULTURE AND RURAL ECONOMY. 321 



test to other potatoes, we may conclude that if one fall to 

 the bottom it is better, or if it rise to the top it is poorer, than 

 the standard. A series of standards has been suggested, 

 therefore, by Dr. Neslee, of definite percentages of salt and 

 water, thus producing a sliding-scale applicable under any 

 circumstances for the test in question. : 8 (?, July 13, 221. 



PEPOET ON THE POTATO DISEASE. 



The Prussian Agricultural Academy has been occupied 

 since 18(T3 in making laborious investigations into the mode 

 of propagation and possible prevention of the potato disease. 

 A report of operations has recently been published, from 

 which it appears that the following points, among others, 

 may be considered as finally determined : First. A relation- 

 ship and connection between the disease of the leaf and of 

 the tuber, and the fact that the potato-fungus is the cause of 

 the wet-rot of the potato. Second. The wintering of the my- 

 celium of the fungus in the diseased tubers is considered well 

 established and as needing no farther verification. The mode 

 of dissemination of the disease, however, is considered as re- 

 quiring additional investigation, including the development 

 of the mycelium of the infected tubers in the superficial por- 

 tion of the young plant, as well as the formation of the leaf 

 fungus. The inquiry is suggested also whether the first 

 traces of the leaf disease in the summer come from the my- 

 celium of the infected seed-potatoes of the previous year. 

 Experiments are also proposed for ascertaining whether, if 

 the young plants are completely protected from the entrance 

 of fungus-spores from the exterior, a diseased mother bulb 

 would produce diseased plants. The effort to find some con- 

 venient mode of disinfection of seed potatoes for the purpose 

 of preventing the disease has not, so far, met with any satis- 

 factory result. It is possible, of course, to destroy the myce- 

 lium of the fungus in the tuber by various means, but this 

 generally injures the bud at the same time and prevents its 

 growth. 



One very important feature accomplished by these inquiries 

 is the ascertaining that different varieties of potatoes vary ex- 

 tremely in their susceptibility to disease, some kinds being 

 much easier of infection than others. It is sim-crested that 

 the collateral inquiry be carried out for the determination of 



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