36 
BULLETIN" 879, U. S. DEPARTMENT OF AGRICULTURE. 
healthy cucumber plants by the method described on pages 30 to 32. 
The fruits used as inocula were of various ages, including young fruits 
about 1J inches in length, large, partially mature fruits that were 
beginning to turn yellow, and yellow and matured fruits such as are 
collected for seed. The very young and the partially mature fruits 
showed the presence of the virus in all cases (Table XIII) , and while 
the inoculations from the mature fruits were not so constantly suc- 
cessful they produced the disease in a number of plants. The pres- 
ence of the virus in the ovule itself has not been demonstrated, as it 
is difficult to remove the ovules from a watery fleshy fruit like the 
cucumber without carrying traces of the juices of other parts of the 
fruit. 
Table XIII. — Results of inoculations with crushed tissues of mosaic cucumber fruits of 
various ages. 
Treatment. 
Inoculum, crushed 
tissues of— 
Point of inocula- 
tion. 
Number 
of plants 
inocu- 
lated. 
Results. 
Date inocu- 
lated. 
Number 
of mosaic 
plants. 
Date last 
observed. 
Sept. 10, 1917 
Do 
Inoculated . . . 
do 
Young mosaic fruit 
Partly mature mosaic 
fruit. 
Mature, yellow mosaic 
fruit. 
Base and tip of 
stem. 
do 
do 
do 
5 
6 
5 
8 
10 
10 
10 
10 
3 
4 


6 
3 
4 

Sept. 21, 1917 
Do. 
Do 
Do 
do 
Control 
Inoculated . . - 
do 
Do. 
Do. 
Sept. 20, 1917 
Do 
Young mosaic fruit 
Partly mature mosaic 
fruit. 
Mature, yellow mosaic 
fruit. 
Healthy fruit 
.....do 
do 
do 
do 
Oct. 14, 1917 
Do. 
Do 
do 
Do. 
Do 
Control 
Do. 
VIRUS IN THE MATURE SEED. 
Although the young fruits and even fruits at maturity may have 
the virus present, as is shown in Table XIII, it has never been de- 
tected in any portions of the seed which have been removed from the 
fruit and subsequently dried. The drying process probably accounts 
for its absence from the seed coat, since the juice of mosaic cucumber 
plants soon loses its infectious quality if subjected to desiccation. 
Tests have been made of both seed coat and embryo in 37 inocula- 
tions, the material being crushed in sterile distilled water and both the 
water extract and the crushed tissue used for inoculation, but no infec- 
tion has ever occurred. Allard (3) has found that the virus of tobacco 
mosaic may be present in the mature dry seeds of mosaic tobacco 
plants, and this is consistent with the fact that the virus of tobacco 
mosaic is more resistant to drying than that of cucurbit mosaic. At 
the present time, however, there is rather definite proof that the mosaic 
disease of cucumber may be carried over in the seed. (PL I, A.) If 
such is the case, it is possible that the virus is occasionally present in 
the seed, although perhaps so rarely that a large number of inocula- 
tions would be necessary to demonstrate its presence. 
