1896 | TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 129 
were immersed in the solution, and the beaker covered by a cork 
to prevent evaporation (jig. 6). 
In all of the experiments performed two seedlings were used. 
Before placing them in the solutions they were allowed to grow 
until the roots had reached a length of about 20™,and then 
a distance of 15™™ was marked off from the tip of each 
root by means of a fine brush and India ink. The time was 
then recorded, and at twenty-four hours from that time, the 
seedlings were removed from the solutions and measured again 
and the growth recorded. The roots were also carefully exam- 
ined for any other symptoms of poisoning besides the retardation 
or inhibition of growth. They were then replaced in the solutions 
and allowed to stand for another twenty-four hours when measure- 
ments were again made. In all cases the seedlings were om in 
a dark chamber with nearly a uniform temperature (21°-23° C. ) 
~The lengths given in the tables are the average growth per twenty- 
four hours. 
The mixture of the solutions for the growth of seedlings was 
made as follows: 
10° of nor. sol. to 1000" =, 7. 
100° of , <0 to 200°%= hh, 
100° of ,N,,, to 200°=_ipy ete. 
3. H-acips. 
Two seedlings of Pisum sativum were placed in each of the 
Solutions of the strengths shown in the table and the growth 
recorded for forty-eight hours. 
N 
sara +300 a yeu 7ys00 
Hey.) 14 24 hours.) 5... 3.25™" 475°" 
OG 34 hoe oo ee ee 5 ae 
Hiscy }18t 24 hours. i) 25. %. 5° 125° * 
OH DOG ce hs 86 ie ees 5.25 
HNO ee ee WOGIR oe ok ees ‘ 65 
Te ae Oe WS eS oe eee oo 
HBr oe DOR be oO a ae Tah 
6 4 Ware ee 6.25 “ 
