226 NISHIMURA: A CARRIER OF THE MOSAIC DISEASE 
The third series were inoculated on August 10 by method No. 4, the 
plants having seven to eight leaves. Forty-eight of these showed 
the symptoms of disease. The incubation period was from six to 
seven days in each of the series. The mosaic symptoms always 
appeared on the first or second new leaves that were formed after 
inoculation. Fifteen controls were kept in each experiment and 
after twenty-five days they were found to be in a healthy condition. 
The incubation period is seen to be much the same in all the ex- 
periments: 
Pee: experiment No. 2, from 7 to 9 days; 
In experiment No. 3, from 7 to 11 days; 
In experiment No. 5, from 6 to 10 days. 
This result agrees with the observations of other authors on 
the length of the incubation period. In each experiment the 
mosaic was observed on the first or second new leaf which appeared 
after inoculation. : 
The appearance of the mosaic leaves of apple of Sodom and 
tobacco, infected through the alkekengi, is the same in design and 
coloring (i. e., distribution of the dark green with relation to the 
vein, etc.) as in direct infection from tobacco to tobacco. 
There can be no question that the virus induces the same symp- 
toms after passing through the apparently immune plant as when 
transferred directly from one susceptible plant to another. The 
affected plants developed the disease on all new leaves which 
appeared after inoculation. 
6. Transfer of mosaic from the apple of Sodom to the alkekengi and 
then back to the apple of Sodom 
The transfer through P. Alkekengi from apple of Sodom to 
apple of Sodom is equally easy. 
June 23, ten young healthy plants of apple of Sodom (3-4 
inches high) were inoculated with the juice from the leaves of the 
- same plants of P. Alkekengi (inoculated from apple of Sodom) 
which were used in experiment No. 2 as a source for the inoculation 
of tobacco. I used method No. 5 for this inoculation. June 30, 
plants 2 and 6 showed mosaic on the first new leaves. July 1, 
plant 4 showed mosaic on the first new leaf. July 2, plants 7 and 
