32 
BULLETIN 195 ; U. S. DEPARTMENT OF AGRICULTURE. 
from selection work is the weeding out of these undesirable strains. 
It is not at all unlikely that from 5 to 10 per cent of weak, diseased, 
or unproductive plants may be found in all unselected seed potatoes. 
It is also equally certain that in nine cases out of ten in ordinary field 
Average 
Bb/s ofpr/mes per /Sere - 22. 66 
• - cu//s - • -24.86 
Bb/s of primes per Acre — /O. /2 
■ cu//s - " ' -2676 
Bb/s ofpr/mes per Acre - 28. /6 
■■ cu//s " " -3938 
Bb/s ofpnmes per /icre — 20.90 
- - cu//s ' . - -20.90 
Bb/s of primes per /lore — O.OO 
• " GU//S ■■ ■■ - 22 20 
Bd/s ofpnmesperAcre — 8538 
- cc/Z/s - " - 3058 
Bb/s of primes per Acre 
CU//S 
Bb/s of primes per Acre 
■■ CU//S " -* " 
73.66 
36.32 
- /7.3a 
49.9 O 
Bb/s ofpnmesperAcre 
■■ CU//S 
-33.32 
- 29-48 
Bb/s ofpr/mes per Acre — 60.06 
■ ■ cu//s - - 3564 
Bb/s of primes per Acre — 34/2 
■ " cu//s - ' -33.64 
Bb/s ofpr/mes per Acre — //330 
" " co//s - - — 3674 
/36/sofpr/mesperAcre —3338 
" ■ cu//s - • - 4796 
Bb/s ofpnmesperAcre — 6793 
• - cuffs - " — 28.6/ 
Bb/s of pr/mes per Acre — 80.74 
■ cu//s - - - 30.58 
Fig. 2. 
Bb/s ofpnmes per Acre — 65 78 
■ co//s ■ " -24.42 
Esai Primes .t=i Cuffs 
-Diagram showing the hill-selection performance record, season of 1912. 
practice these are unrecognized, because the weak or diseased plants 
are scattered here and there throughout the field and are obscured 
by surrounding healthy plants. Their resultant effect on yield is 
also unnoted and will probably remain so until we demand a practi- 
cally perfect stand. 
