1032 
Journal of Agricultural Research 
Vol. XXIV, No. la 
rate of 20 cc. per gram of tissue. The extract was filtered and various 
dilutions of the filtrate with distilled water were used as media for spore 
Onion Scale Extract 
White red yellow 
Fig. 3. —Spore germination of Colletotrichum circinans in extracts made from dry outer scales of white, 
red, and yellow varieties of onion, and in onion decoction. One gm. of dry scale was extracted over night 
in 20 cc. of distUled water at room temperature. Dilutions were then made up to i to s with distilled 
water. Note t^t germination and growth were normal in onion decoction and undiluted white scale 
extract, while in the undiluted colored scale extract typical abnormal germmation occurred as shown in 
fig. X. With dilution the toxicity of the extract was reduced, however, quite normal germination occur¬ 
ring at I to 5. Normal tmgerminated spores are shown in the lower left-hand comer. See further expla¬ 
nation in the text. 
germination. The results are recorded below; representative spores 
from each dilution are illustrated by camera lucida sketches in figure 3. 
White scale tissue; 
Undiluted—Good germmation, growth, and appressorium formation. 
