14 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 
The decrease in stand both with decreasing amounts of watering 
and with increasing amounts of acid was sufficiently consistent in 
this experiment to establish beyond a reasonable doubt the relation- 
ship, both of the amount of acid used and of the amount of watering 
done, to the acid injury. In the weakest acid plat with the inter- 
mediate watering, no appreciable injury occurred. Because of the 
variation in germination aside from the influence of acid, the results 
were not always quite as consistent as in this series, but no reason has 
been found to doubt the relation between the amount of acid and 
the extent of injury in beds treated at sowing. 
INJURY TO PINES BY SULPHURIC ACID APPLIED BEFORE SOWING. 
In treating beds with sulphuric acid to kill fungous parasites the 
attempt was made to evade toxic action on the seedlings by applying 
the acid a number of days before sowing. Jack pine was also used 
in most of these tests. In such cases the beds were ordinarily hoed 
and raked just before they were sown, so that the upper 2 or 3 inches 
of soil was well mixed after the acid was applied. In the plats treated 
at sowing there was the possibility that the injury was limited to the 
surface five-eighths of an inch of soil, simply because this layer of 
soil had acted as a trap for the acid, absorbing most of it at the time 
of application. In the case of plats treated before sowing there was 
no such possibility. The seeds were in most cases covered with about 
one-fourth of an inch of soil taken from the upper 1 to 1J inches of 
the soil of a near-by area that had been given the same treatment as 
the plat sown. Considerable injury occurred in plats which received 
0.25 and 0.375 ounce of acid nine days before sowing (20 days in all 
elapsing before germination), although the treated plats received 
approximately 1.6 inches of water five days after sowing, followed by 
0.3 to 0.4 of an inch daily till after germination. The slight drying 
of the surface soil which resulted in the injury on these plats took 
place the first day after germination, 21 days after the application of 
the acid. 
In another series, using the same species of pine, amounts of 
0.281, 0.375, and 0.687 ounce of acid per square foot were applied 11 
days before sowing, two plats receiving the latter amount. Four 
days after sowing, the plats were given approximately 1.6 inches of 
water, followed by waterings of approximately 0.3 to 0.4 inch on 
the sixth, eighth, ninth, tenth, and eleventh days from sowing. 
Germination took place on the eleventh day, 22 days after the 
application of the acid, and on the morning of this day the soil 
surface became somewhat dry, but not dry enough to cause appre- 
ciable drought injury in the nonacid plats. As shown by later 
examination of the length of the acid-injured roots, injury took 
