INFORMATION" SECURED BY A CIRCULAR OF INQUIRY. 33 



In view of the limited number of varieties tested and the consequent 

 restricted scope of observation, it would hardly be justifiable as 3^et to 

 give an expression of opinion as to the probable outcome of such a line 

 of investigation. These observations are to be continued on a much 

 larger scale the coming season. 



Ilifrrid ami other xeeiUlngs. — Seedlings were grown in 1903 from the 

 Mexican species supplied by Mr. Pringle — S. poJyadeniuiii^ S. stolon l- 

 ferum^ and S. hulhocaatanuw . This number has recently been aug- 

 mented by S. verrxLcosum. and a wild form of 8. tuheroswn. In 1904 

 some of these were successfully hybridized with the cultivated potato. 



While it is yet too early to say very much regarding the possibili- 

 ties of developing a conmiercially desirable disease-resistant variety of 

 potato through the hybridization of wild species with our cultivated 

 varieties, there seems good reason for believing that improvement may 

 result from such crossing, especially as to disease resistance. 



In addition, a large number of seedlings of the common potato were 

 grown in 1901. Among this number several vigorous-growing plants 

 were noted, which remained quite green up to the time of digging. 

 Some 50 of the more promising of these were saved for trial the com- 

 ing season. Selections were based on vigor of vine, size and 3deld of 

 tubers, and freedom from rot. 



One of the most interesting and instructive features of the seedling 

 experiment was the object lesson it presented of the extreme vigor of 

 some of the plants, showing quite plainly that one of the best sources 

 for increasing the vigor lies in the production of new varieties from 

 seed. Proper fertilization and good tillage are also important aids in 

 increasing the vigor and disease-resisting powers of the vine. 



While the data in hand do not warrant broad generalizations, the 

 following inferences are drawn by Professor Stuart: 



(1) Some varieties are less subject to vine injmy than others. 



(2) Some show a greater tuber resistance to rot than others. 



(3) With some there seems to be a fairly close relation between resist- 

 ance of vine to disease and of the tuber to rot. 



(1) Selection has not given visible increase of resistance. 



(5) Hybridization and the growing of seedling plants, followed by 

 careful selection, seem to offer a more logical method of securing 

 disease-resistant varieties than does selection. 



INFORMATION SECURED BY A CIRCULAR OF INQUIRY. 



In order to secure all information possible as to the relative merits 

 of the varieties now before the public, a circular letter of inquiry was 

 sent recently to various experiment station officers and to about two 



