THE MOSAIC DISEASE OF CUCURBITS. 
28 
the desired chemical added in such amount and strength that when 
combined with 5 c. c. of the plant juices it gave the desired concen- 
tration. The tubes were then shaken well and allowed to stand for 
12 hours. Inoculations were made with these inocula, as in the case 
of the dilution experiments, into both the stems and leaves of healthy 
plants. The results shown in Table V indicate that formaldehyde, 
phenol, mercuric chlorid, and copper sulphate in dilute concentra- 
tions were all toxic to the mosaic virus. 
The tests with copper sulphate gave definite mosaic infection in 
one case, but the writer is of the opinion that this is not an indica- 
tion that the juices are resistant to its action, since the same and 
weaker dilutions have destroyed the virus in all the other tests. The 
results in this single case, however, were apparently not due to out- 
side infection, as the plants were caged from the beginning of the 
season. Chloroform in a 10 per cent mixture destroys the activity 
of the virus, but a 5 per cent chloroform mixture seems to be 
harmless. Toluene in a 10 per cent mixture has no apparent effect. 
In the case of these chemicals special care was used to mix the. solu- 
tion thoroughly, and the tubes were kept tightly corked until inocu- 
lations were made. The 10 per cent solution represents a large excess 
and the 5 per cent a slight excess beyond the possibilities of absorp- 
tion by the plant juices. The results of these tests have been 
consistent in most respects, however, as is shown in Table V, and 
indicate that the virus is not resistant to ordinary disinfectants. 
Table V. — Effect of chemicals on the -power of infection of the expressed juices of mosaic 
cucumber plants. 
Chemical and strength used. 
Number 
of plants 
inocu- 
lated. 
Results. 
Date inoculated. 
Number 
of mosaic 
plants. 
Date ob- 
served. 
Series I (field experiments): 
Aug. 10, 1917. 
Formaldehyde 1 per cent 
4 
4 
4 
4 
4 
4 
4 
4 
5 
5 
5 
5 
5 
5 
5 
5 
7 
7 
7 
7 
7 
7 
7 


3 


3 
4 






3 
3 





2 
4 
5 

Aug. 20, 1917. 
Do 
Phenol 1 per cent 
Do. 
Do. 
CuS0 4 1 per cent. 
Do. 
Do.. . 
HgCl 2 1:1,000 
Do. 
Do. 
Do. 
Do.. . 
Toluene 10 per cent 
Do. 
Do.. . 
Untreated juice 
Do. 
Do. 
Distilled H 2 (control) 
Do. 
Series II (greenhouse ex- 
periments): 
Oct. 23, 1917 
Formaldehyde 1 per cent 
Oct. 31,1917. 
Do.. . 
Phenol 1 per cent 
Do. 
Do. 
CUSO4 1 per cent 
Do. 
Do.. 
HgCl 2 1:1,000 
Do. 
Do. 
Do. 
Do. 
Toluene 10 per cent 
Do. 
Do 
Do. 
Do. 
Distilled H 2 (control) 
Do. 
Series III (greenhouse ex- 
periments) : 
Mar. 28, 1918 
Formaldehyde 0.5 per cent 
Apr. 20, 1918. 
Do 
Phenol 0.5 per cent 
Do. 
Do 
Do. 
Do 
HgCl 2 1:2,000 
Do. 
Do 
Do. 
Do 
Do. 
Do 
Do. 
Do 
Distilled H96 (control) 
Do. 
, 
