210 
Journal of Agricultural Research voi. xxiii, no. ^ 
Table IV.— Resistance of the coverings of Johnson grass caryopses to the action of 50 per 
cent chromic acid 1 
Seed lot 37001. 
Condition of caryopses: 
Apparently not affected, or slightly darkened 
or mottled over embryo. 
Portions of embryo or its coverings (espe¬ 
cially axial organs) more or less darkened or 
many after more than 1 or 2 days’ treatment 
with part of embryo eaten away. 
Parts of endosperm eaten away through weak 
place in covering on flat side, usually oppo¬ 
site the embryo. 
Germination percentage at 26° C.: 
1 day. 
2 days.. 
3 days.... 
Total germination after unscratched period 2 . 
3 days 2 . 
4 days 2 . 
6 days 2 . 
Total viable. 
Effect of varying length (days) of treat¬ 
ment with chromic acid. 
Per ct . 
65 
3 
o 
68 
32 
o 
Per ct. 
45 
50 
40 
4 
o 
44 
45 
Per ct. 
12 
83 
12 
2 
I 
15 
15 
Per ct. 
7 
93 
Per ct. 
2 
98 
Seed lot from San Antonio, 1917- 
Effect of varying length (days) of treat¬ 
ment with chromic acid. 
Condition of caryopses: 
Apparently not affected, or slightly darkened 
or mottled over embryo. 
Portions of embryo or its coverings (espe¬ 
cially axial organs) more or less darkened or 
many after more than 1 or 2 days treatment 
with part of embryo eaten away. 
Parts of endosperm eaten away through weak 
place in covering on flat side, usually oppo¬ 
site the embryo. 
Germination percentage at 26° C.: 
1 day. 
2 days... 
3 days. 
Per ct. 
48 
II 
I 
Total germination after unscratched period 2 
60 
3 days 2 . 
4 days 2 . 
6 days 2 . 
40 
o 
Total viable. 
Per ct. 
65 
34 
44 
16 
1 
61 
63 
Per ct. 
26 
73 
15 
6 
23 
Per ct. 
22 
78 
24 
17 
Per ct. 
94 
