3 
PRODUCTIVENESS AND DEGENERACY OF THE IRISH 
POTATO* 
Preliminary Studies mostly within the Pearl Variety. 
By C. L. Fitch, Potato Specialist. 
There is every reason to believe that principles true of one variety 
will be fundamental to all varieties of Irish potatoes. We submit these 
observations, however, in their bearing upon one variety only. 
Cause of Tuber Degeneracy .—We find that within the Pearl 
variety, tubers become deep eyed, knotty, long and unproductive 
because of conditions that make the whole plant tend toward going 
to seed. Attention is called to the tendency of the tubers, which 
are enlarged stems, to be controlled in shape by the general habit of the 
plant. We also trace the branch and leaf habits which parallel tuber 
productiveness and degeneracy, giving drawings of the typical charac¬ 
ter of vines and corresponding photographs of tubers and using aerial 
tubers as proofs that certain tuber parts correspond to certain portions 
of other potato stems. 
Sexual Tendencies .—We find the indicated factors of the tendency 
towards bearing seed to be early dryness, close and deep cultivation, 
and disease. We find that tuber productiveness in Pearls is in- 
* The following is essential to the argument but not a part of it. 
THE PEARL, PEOPLE’S, AND THE BLUE VICTOR, IDENTICAL 
EXCEPT IN COLOR. 
The Pearl originated and still comes by bud variation from the Blue 
Victor. Of this family is the People’s variety. All are alike in shape,, 
excellent keeping quality of the tubers, quick sturdy growth, and medium 
time of ripening. 
The vines and leaves, branching habit and tuber arrangement are 
alike in the three sorts, with the exception of the darker color of the 
whole Blue Victor plant, as might be expected from the tuber color. 
The differences in the tubers of the three sorts consist in color and 
the character of the outer skin. The Blue Victor is of a purple color 
which, on exposure to the light, fades to a leaden brown, and is often 
streaked with white. This usually appears to be due to cracks in the skin, 
but sometimes appears to be the real outside color by variation, and when 
so covering an eye comes true in most cases both in the first propagation 
and in the succeeding crops of Pearls. The Pearl is brownish white with, 
at best, a well russeted skin, but there are often smooth spots on russeted 
Pearls, or whole crops that are nearly unrusseted. In the People’s variety 
a deeper brown characterizes even the unrusseted skin of tubers, and both 
the russeted and the smooth skin appear to be thicker. On all the three 
sorts there are spots on occasional tubers, or more rarely whole tubers, 
which resemble and are identical with each of the others,—including blue 
spots or blue potatoes from both the Pearl and the People’s. The color 
concentrated at the dormant sprout tips of the three sorts of tubers, at 
y' 
[A, • 
