10 BULLETIN 1029, U. S. DEPARTMENT OF AGRICULTURE. 
injury resulted to commercial seed held at this temperature for as 
short a time as 5 minutes. At 50° C. the fungus was killed in 30 
minutes with the small number of seeds used, but here, again, 
some detrimental effect upon commercial seed occurred ; in fact, seed 
injury was evident in somewhat milder treatments than those reported 
by Norton (8). This is probably due to differences in the suscepti- 
bility of individual seed lots. Soaking the seed in water before treat- 
ment did not appear to be of any distinct advantage. At present, 
hot-water treatment does not appear to be sufficiently superior to the 
mercuric-chloric! treatment described later to warrant its recom- 
mendation for general use. Further comparative trials, however, 
should be made. 
MERCURIC-CHLORID SOLUTION. 
Solutions of mercuric chlorid were made bv dissolving: the chemi- 
cally pure salt in distilled water. The treatments were all conducted 
at room temperature, about 20° C. Four methods were used: (1) 
Soaking the cabbage seed in the disinfectant without previous treat- 
ment and rinsing once in clean water after removal; (2) soaking 
in the disinfectant without previous treatment and allowing the seed 
to dry without subsequent rinsing; (3) soaking in water for one 
to four hours before placing in the disinfectant and rinsing once in 
clean water after treatment; (4) dipping the seed first in alcohol 
for two minutes, then transferring to the disinfectant for the desired 
time, and finally rinsing in clean water. Mercuric chlorid caused a 
gradual reduction in the percentage of germination of seeds propor- 
tionate to the length of soaking and the concentration of the solu- 
tion. Injury to the germinating seedlings was characterized by tem- 
porary or permanent stunting of growth and varied amounts of 
necrotic tissue extending back from the margins of the cotyledons. 
The results of experiments with mercuric-chlorid solutions are pre- 
sented in Table IV. 
With the first method (soaking in the disinfectant and rinsing in 
water) little injury resulted from a 30-minute treatment with the 
1 : 500 solution, and practically none from less severe treatments. In 
the case of one lot of imported cabbage seed of rather low vitality 
(not cited in Table IV), considerable injury resulted from the 30- 
minute 1 : 500 treatment, indicating that treatments as severe as this 
should be used with caution. In the case of most lots of cabbage 
seed, however, the soaking may be prolonged to one or two hours with 
only slight injury, and at three hours only medium retardation 
may be expected. These stronger treatments completely eradicated 
the fungus in the case of the No. ±-18 seed. The fungus in the No. 
1-19 lot appeared to be much more resistant to this chemical. 
