6 o6 
Journal of Agricultural Research 
Vd. XXIII, No 8 
/=&?G£n 
O /0 20 <30 <20 SO 60 70 SO 90 /00 
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Fig. ii.—G raphic presentation of Table XXIII, showing the relation of moderately diseased and nearly 
disease-free seed to the percentage of vigorous, semi vigorous, and weak plants produced, and to yield 
of marketable and unmarketable com in bushels per acre. 
Fig. i2.—Graphic presentation of Table XXIV, showing the relation of moderately diseased and nearly 
disease-free seed to the percentage of vigorous, semivigorous, and weak plants produced, and to yield 
of marketable and unmarketable com in bushels per acre. 
The standard for vigorous plants in 1921 was somewhat different from 
that used during the previous three years of the investigations. On 
this account percentages of vigorous plants in 1920 can not be compared 
with percentages of vigorous plants in similar composites in 1921. How¬ 
ever, the standards for vigorous, semivigorous, and weak plants were 
reasonably constant throughout each season, especially within any given 
experiment. 
The soil was cold at the time the first planting was made and continued 
rather cold for 8 to 10 days. In this connection it is interesting to note 
that the field stand of the com grown from moderately diseased seed is 
12.2 per cent lower than that grown from the nearly disease-free com¬ 
posite (see Table XXI). By referring to Table XXV and figure 14 it 
