Injury by disinfectants to seeds and roots. 15 
place at this time. It was most serious in the 0.375-ounce plat, 
mainly because it had become somewhat drier than the rest. Even 
the 0.281-ounce plat seemed more injured than the 0.687-ounce 
plats, which were not seriously affected. Thi activity of parasites, 
mostly, probably, Pythium debaryanum, in the soil in these plats 
during and after the time that this injury was occurring to the 
seedlings is a matter of some interest. The slight relationship 
between the amount of acid used and the amount of injury taking 
place in these plats 22 days after treatment emphasizes what has 
already been said as to the apparent equalization of strength of 
acid solutions of different original strengths in the soil as the con- 
centration decreases. 
Plats of jack pine which had been entirely killed by applications 
of 0.172 ounce of acid at the date of germination and 0.086 ounce 
six days later, 0.258 ounce in all, were resown with the same species 
23 to 24 days after the first treatment, germination taking place 
34 to 36 days after the first treatment. No serious injury occurred 
to the seedlings in this second sowing, though no special wataring 
was given. Similar results were obtained with yellow pine in plats 
treated with 0.3 ounce of acid 39 days before sowing (50 days before 
germination), no serious injury occurring despite the entire lack of 
any special watering. In all cases, acid applied before sowing can 
be kept from causing injury quits easily by the watering methods 
used for beds treated at sowing. The tests indicate that if germina- 
tion takes place at any time during the first month after 0.25 ounce 
of acid is applied to the beds it will be necessary to give more than 
the usual nursery watering during the germination period in order 
to insure freedom from injury^ to the seedlings. Though it is some- 
what easier to prevent acid injury in beds treated several days 
before sowing, treatment at the time of sowing is so much more 
effective against the damping-off parasites that it is considered 
preferabb. 
RELATIVE RESISTANCE OF VARIOUS SPECIES OF PINE TO SULPHURIC ACID. 
There was considerable difference in the amount of injury caused 
by similar acid treatments on different species of pine. Jack pine, 
as a rule, seemed most liable to serious injury, while yellow pine was 
least often damaged, and Norway and Corsican pines were intermedi- 
ate. The resistance of yellow pine as compared with jack pine was 
especially evident in beds treated shortly after germination. Most 
of this apparent difference in resistance is due not to variations in 
the capacity oi the root tips to endure acid, but to a difference in 
the rate of growth. Yellow pine has a seed approximately ten 
times as heavy as that of jack pine and sends its root down much 
