1917] 
FREIBERG—MOSAIC DISEASES 191 
pressed from diseased leaves and filtered through Berkefeld 
filters, and with sterile water. Four plants were used in each 
case. At the end of 17 days, 3 plants inoculated with the 
secretion were diseased, while all 4 of the plants inoculated 
with the filtered juice of diseased leaves showed mosaic. The 
4 checks remained healthy. 
This experiment was repeated on July 7, 1916, an entire 
plant being used for secretion. This necessitated the use of 
larger vessels, etc., which increased chances for contamina- 
tion. The secretion obtained in this case had been badly fer- 
mented by bacteria, and inoculation experiments gave nega- 
tive results. 
The writer’s time then became occupied with a field ex- 
periment and a repetition of the above had to be deferred. 
It was repeated, however, on September 6, 1916, the secretion 
phase of the experiment being allowed to run until October 19. 
Inoculations were made on October 22, 6 plants being used. 
After 15 days 2 of the 6 plants inoculated with the secretion 
showed mosaic, while all 6 inoculated with sterile tap water 
were healthy. Inoculations were not made with juice of dis- 
eased leaves as in the first experiment. There is reason to 
believe, from the uniformity of the results obtained with 
secretions, that some of the infectious substance was dissolved 
in the sterile water used for subsequent inoculations. Each 
secretion was tested for oxidases by adding hydrogen per- 
oxide and guaiacum, as did Woods, but no oxidases were de- 
tected. No indisputable conclusions could be drawn from 
these results, since these experiments were only preliminary, 
but because of their uniformity, they furnished considerable 
encouragement towards investigating further the possibility 
of securing an extract possessing infectious properties but 
no oxidase activity. 
On a priort grounds it seemed scarcely possible that sub- 
stances such as oxidases found naturally and so commonly in 
plants should, when injected into other plants, be able to pro- 
duce such a disorder as the mosaic disease. It will be recalled 
that Allard (715%) was able to produce the disease even at a 
dilution of 1:10,000. One can easily see, however, how a sub- 
