1026 
Journal of Agricultural Research 
Vol. XXIV, No. 12 
here that there is a certain amount of pigment present in the epidermal 
cells of the colored fleshy scales which was necessarily included in the 
extract. Moreover, it will be shown later that the water extract of dry 
pigmented scales is toxic to the fungus. It is believed, however, that 
in these fleshy scale extracts the pigments were so dilute as to have had 
little or no effect. Various dilutions of the fleshy scale extracts in dis¬ 
tilled water were secured, as before, and their effect upon germination 
of spores was determined. As described in the previous experiment, a Petri 
dish containing one slide for drops of spores suspended in distilled water 
and one slide for spores in the onion extract, was used for each dilution. 
Results of this experiment are included in Table IV. 
TabIvH IV .—Toxicity of succulent scale extract from White, Yellow, and Red Globe 
varieties of onion to the spores of Colletotrichum circinans 
Dilution. 
Undiluted... 
I to lO 
I to 20 
I to 40 
I to 60 
I to 80 
I to 100, 
I to 1,000.... 
spore germination. 
1 
Petri 
dish 
No. 
Medimn. 
Experiment i. 
Experiment 2. 
White. 
Yellow. 
Red. 
White. 
Yellow. 
Red. 
fHxtract. 
0 
0 
0 
I 
\Distilled water. 
0 
0 
0 
/Kxtract... 
0 
0 
0 
2 
\Distilled water. 
0 
0 
0 
fHxtract. 
0 
0 
0 
0 
0 
0 
3 
\Distilled water. 
++ 
0 
++ 
0 
+ + 
0 
© 
0 
© 
0 
fHxtract. 
0 
0 
4 
\Distilled water. 
++ 
© 
+ + 
© 
0 
0 
fHxtract. 
0 
V-./ 
0 
0 
5 
\Distilled water. 
© 
0 
++ 
0 
e 
0 
fHxtract. 
6 
[Distilled water. 
© 
0 
++ 
0 
4 - 4 - 
0 
fHxtract.. 
7 
[Distilled water. 
4 - 4 - 
0 
++ 
0 
4 - 4 - 
0 
8 
fHxtract... 
[Distilled water. 
++ 
0 
++ 
0 
4 - 
0 
fHxtract. 
9 
[Distilled water. 
++ 
0 
+4- 
© 
+4- 
-1- 
4-4- 
4- 
-1-4- 
4-4- 
4-4- 
4-4- 
4-4- 
4-4- 
0 
fHxtract. 
10 
[Distilled water. 
4-+ 
0 
4-4- 
© 
4-4- 
© 
fHxtract. 
II 
[Distilled water. 
-f-f 
fHxtract. 
12 
[Distilled water. 
+4- 
4-+ 
fHxtract. 
+ + 
+ + 
+ + 
+4" 
++ 
++ 
+4- 
++ 
+ 
++ 
+4- 
+ 
+ + 
4-4- 
4-+ 
++ 
4-+ 
++ 
4-f 
4-4- 
0 
4-4- 
© 
13 
[Distilled water. 
-f+ 
0 
4-+ 
fHxtract. 
14 
[Distilled water. 
4-4 
fHxtract. 
15 
[Distilled water . . . 
16 
fHxtract. 
[Distilled water. 
1 Symbols used: o=»no gennination; 0 =o to 25 per cent spores germinating; --=»2S to 50 per cent; 0=50 
to 75 per cent; +=■ 75 to 90 per cent; 4 -+=90 to too per cent. 
It is quite evident that but little difference exists between the colored 
and white Globe varieties used as to the toxicity of their cell sap. In 
fact, in this respect the differences between individual bulbs of the same 
