BOTANY: 0. L. RABER 
683 
tartrate of sodium. The effects of the single salts and of various mix- 
tures were studied. Of especial interest are those combinations of salts 
which show increased toxicity in the mixtures. As an example of these 
we may take the effects of sodium chloride and sodium citrate. 
Solutions of these salts were made of the same electrical conductivity 
as the sea water (about 0.52M sodium chloride and about 0.58M sodium 
citrate) . On placing tissue in the pure chloride we find that after about 
three hours the electrical resistance falls to about 10% of the original 
resistance and there remains stationary. This represents the death 
point. In the solutions containing citrate we find that before the re- 
sistance falls as low as 10% the tissue softens so that it can not be ma- 
nipulated. Consequently the experiments with citrate are never con- 
tinued for more than twenty minutes, at which time the resistance of 
the pure sodium citrate reaches about 17% of the original. The drop 
in resistance occurs much more rapidly in the sodium citrate than in the 
sodium chloride. 
TABLE 1 
Per Cent of Original Resistance 
TIME IN 
MINUTES 
100 cc. Cl 
+ 
0 cc. 
CITRATE 
75 cc. Cl 
+ 
25 cc. 
CITRATE 
63 cc. Cl 
+ 
37 cc. 
CITRATE 
50 cc. Cl 
+ 
50 cc. 
CITRATE 
37 cc. Cl 
+ 
63 cc. 
CITRATE 
25 cc. Cl 
+ 
75 cc. 
CITRATE 
0 cc. Cl 
+ . 
100 cc. 
CITRATE 
per cent 
per cent 
per cent 
per cent 
per cent 
per cent 
per cent 
5 
92 
67 
55 
48 
47 
45 
36 
10 
85 
47 
39 
31 
30 
29 
24 
15 
82 
37 
30 
24 
21 
21 
20 
20 
80 
30 
21 
17 
16 
17 
17 
The above represents the average of ten experiments. 
Table 1 (in which the resistance is expressed as per cent of the origi- 
nal resistance in sea water) shows the fall of resistance in the various 
solutions. The table shows that at 23°C. (the temperature varied be- 
tween 22° and 24° during the experiment) the resistance in sodium cit- 
rate fell in the course of the twenty minutes to 17% of the original 
resistance while during the same time in sodium chloride it had fallen 
to only 80%. In the mixtures intermediate conditions are observed. 
The significance of these results is shown more clearly by the figure 
(fig. 1). Here is plotted the set of values obtained for the fifteen minute 
curve. The curve, A, is the curve of resistances found as shown in the 
table. The curve, B, is the curve of the additive effect which is ob- 
tained by diluting the citrate with water and to this adding the com- 
parative dilution effect of the chloride according to the method outlined 
by Osterhout.^ 
