94 
Journal of Agricultural Research voi. xxvn, No. * 
That the variation in percentage of seed transmission of mosaic was 
not dependent upon the date of infection of the parent plant is indicated 
by the fact that in the 19 Midwest parent plants recorded in Table III 
the mosaic was of seed origin, and yet an average of only 10 per cent of 
mosaic occurred in the progenies of these plants; in fact, in eight progenies 
no mosaic occurred. In 4 of the 8 Haberlandt parent plants the mosaic 
was also of seed origin and the progenies of these plants showed a lower 
average percentage of mosaic than the progenies of the other four plants. 
The effect of age of seed upon the transmission of mosaic is of practical 
interest. The field tests noted above proved that the disease persisted 
in the seed from one season to the next. Among 1,105 Haberlandt 
seedlings grown in the greenhouse in December, 1922, from commercial 
seed 15 months old, 3.2 per cent were mosaic. To test the effect of an 
extra year’s storage, commercial seed from two of the same lots tested 
in 1921 (Haberlandt and Arlington, Table I) was planted in the field 
in 1922. Of the 560 Haberlandt seedlings, 7 were mosaic and of the 
629 Arlington seedlings 2 were mosaic. It thus appears that the dis¬ 
ease was present in 2-year-old seed. 
That 2-year-old seed may carry the mosaic disease was further demon¬ 
strated by greenhouse tests in the spring of 1923 with seed harvested from 
single mosaic plants in 1921. The results, as shown in Table IV, indi¬ 
cate that there was a considerable percentage of mosaic transmission 
in the old seed from mosaic plants in the Black Eyebrow and Midwest 
varieties and a low percentage in the Haberlandt variety. 
Table IV .—Presence of mosaic in seed stored 16 montfis 
Plant. 
Variety. 
Per cent 
germina¬ 
tion. 
Number of 
seedlings. 
Number of 
mosaic. 
j 
Per cent 
mosaic. 
I 
Haberlandt. 
77 
88 
3 
3-4 
2 
Black Eyebrow. 
35 
21 
3 
14.3 
3 
Wea. 
75 
40 
O 
0 
4 
Lexington. 
77 
3 i 
O 
O 
5 
Arlington. 
28 
*9 
O 
O 
6 
14 
14 
O 
0 
7 
Midwest. 
64 
38 
26 
68.4 
8 
98 
46 
3 
6 *5 
9 
69 
22 
6 
27.2 
In the summer of 1923, seed from six mosaic Midwest plants collected 
in 1921 was planted in the field and 36 of the 208 seedlings, or 12 per 
cent, came up showing mosaic. These results indicate that the use of 
2-year-old seed can not be recommended as a mosaic control measure. 
In 1921 and 1922 a conspicuous brown mottling of the seed coat occurred 
rather generally and occasioned considerable concern among the growers 
of soybeans for seed. As yet no relationship has been established 
between this seed mottling and the mosaic disease. Mottled seeds have 
been produced by both healthy and mosaic plants and in germination 
tests a few mosaic seedlings were obtained from clean as well as from 
mottled seeds. 
Ordinarily the seed from plants apparently free from mosaic has 
yielded only healthy seedlings. In a field plot in 1922 planted with 
such seed, no mosaic occurred among the 590 seedlings, while in another 
