416 BULLETIN No. 127. [August, 



England that northern grown seed is the superior, and should be 

 obtained every two years or so because of degeneration. It is 

 interesting to note that in experiments at six stations* in the early 

 nineties, all show results slightly in favor of home grown varieties. 

 It is probable that in these experiments more care was paid to seed, 

 fertilizers and cultivation than is usual to growers, resulting well 

 for home grown seed ; nevertheless, had the results been different, it 

 would only have shown, either that 'the northern grown were better 

 adapted to such climate or the soils there found, or that in coming 

 from growers who made a commercial business of supplying seed 

 tubers, they had been given better care in regard to selection and 

 environmental conditions. 



Relying for our conclusions on the philosophical grounds and 

 the practical work of the German and French investigators, it seems 

 tenable that there is no variety senility and that we are warranted 

 in excluding this from our calculations as to commercial methods 

 of producing varieties adapted to certain conditions. The more 

 serious practical question, is the manner in which outside pernicious 

 influences are to be avoided. As methods of cultivation and seed 

 selection are pretty well established and soil, plant food and climatic 

 conditions can be determined and partially controlled in each local- 

 ity, it seems to the writer that here again the matter of disease con- 

 trol is the thing of primary importance. It is questionable, with- 

 out disease resistance or comparatively certain disease control, if 

 expensive work should be done to improve varieties in particular 

 characters such as starch content, by selection of seedlings on the 

 basis of a chemical analysis. For it is reasonably certain that we 

 could not expect this improvement to be transmitted, if we were 

 forced by loss of vigor due to disease attacks to return to sexual 

 propagation. The latter, however, is a matter which we can say is 

 yet unproved. 



^Illinois, Vermont, Maryland, Georgia, Louisiana, and Missouri. 



