THE MOSAIC DISEASE OF CUCURBITS. 
35 
mosaic but showed no symptoms of the disease. No such plant has 
ever shown evidence of containing the virus, as all inoculations from 
them gave negative results, and it is probable that a definite differ- 
ence in susceptibility occurs, depending on the age of the plant. 
LOCATION OF THE VIRUS IN THE PLANT. 
The virus of curcubit mosaic is distributed throughout practically 
all parts of the plant, with the possible exception of the roots. The 
data given in Tables VIII to X show that the juices of stem, leaves, 
and fruits of mosaic cucumber plants are all capable of producing 
infection. All the living leaves of a mosaic plant contain the virus, 
regardless of age or the presence of actual mosaic symptoms, its 
thorough distribution in the leaf cells being shown by the results of 
inoculation by contact of healthy and mosaic trichomes. 
VIRUS IN THE FLOWER PARTS. 
The disease can also be produced by inoculation with the flower 
parts of diseased plants. Inoculations were made with petals, 
anthers, and stigmas of mosaic cucumber plants by carefully dis- 
secting out with sterile instruments the portion of the flower desired 
without breaking other parts and crushing the material in a sterile 
dish with a few drops of sterile water. This crushed mass was then 
used for stem inoculations, the results being positive in each case, 
as shown in Table XII. Allard (3) has shown that the virus of 
tobacco mosaic is also present in the anthers, filaments, and even in 
the placental column and integument of the ovule of infected plants. 
Table XII. — Results of inoculations with the crushed tissues of flower parts of mosaic 
cucumber plants. 
Treatment. 
^ Inoculum. 
Number 
of plants 
inocu- 
lated. 
Results. 
Date 
inoculated. 
Number 
of 
mosaic 
plants. 
Date 
observed. 
Sept. 7,1916 
Do 
Inoculated 
do 
3 
3 
3 
10 
3 
3 
2 
3 

5 

6 

Sept. 23,1916 
Do. 
Do 
do 
Do. 
Mar. 12,1917 
Do 
do 
do 
Mar. 21,1917 
8 
8 
8 
10 
8 
Do. 
Do 
Do... 
Inoculated 
Stigma of mosaic blossom 
Do. 
Do. 
Do 
Do.. 
Inoculated 
Corolla of mosaic blossom 
Do. 
Do. 
VIRUS IN THE FRUITS. 
Inoculations made with the crushed tissues of mosaic cucumber 
fruits have shown that the virus is apparently present in fruits of 
all ages. The inoculum was prepared by removing small portions 
of the tissues close to the ovule with a sterile scalpel and crushing 
them in a sterile dish, the inoculations being made in the stems of 
