Physiology of the Spermatozoa of Ferns . 557 
From the facts embodied in the tables it is evident that 
in addition to malic acid and its salts, a considerable number 
of organic and inorganic salts often occurring in plant cell-sap 
also attract spermatozoa. All the organic salts tested were 
found to attract. These include tartrates, potassium oxalate, 
potassium acetate, and sodium formate. Among the attract¬ 
ing inorganic salts are phosphates, sulphates, potassium nitrate, 
and potassium chloride. 
TABLE I. Isotonic coeff. — 3. 
Standard solutions of ^ 
Potassium nitrate 
f in parts of a mol 
| in grams per cent. 
1 
IO-I 
1 
TIT 
I-OI 
TOT 
O-I 
1 Air 
O-OI 
lDinro 
o-ooi 
ttoVtt 
O-OOOI 
Ammonium hydrogen 
malate 
NH 4 C 4 H 5 0 5 
* 5 * 
R 
R 
R 
rA 
a 
0 
Potassium nitrate 
KN 0 3 
IOI 
N 
A 
a 
0 
0 
0 
Sodium nitrate 
NaNO s 
85 
N 
0 
0 
0 
0 
0 
Lithium nitrate 
LiNO s 
69 
N 
0 
0 
0 
0 
0 
Ammonium nitrate 
nh 4 no 3 
80 
N 
0 
0 
0 
0 
0 
Potassium chloride 
KC 1 
74*6 
N 
A 
0 
0 
0 
0 
Sodium chloride 
NaCl 
58-5 
N 
0 
0 
0 
0 
0 
Ammonium chloride 
NH 4 C 1 
53-5 
N 
0 
0 
0 
0 
0 
Rubidium chloride 
RbCl 
120-7 
N 
A 
0 
0 
0 
0 
Potassium bromide 
KBr 
119.1 
N 
A 
a ? 
0 
0 
0 
Potassium iodide 
KI 
166.1 
N 
A 
0? 
0 
0 
0 
Potassium chlorate 
KCIO3 
122-6 
— 
A 
0 
0 
0 
0 
Sodium formate 
NaCH 0 2 
- 68 
N 
A 
0 
0 
0 
0 
Potassium acetate 
kc 2 h 3 o 2 
98-14 
N 
A 
a 
0 
0 
0 
Organic substances which act indifferently are grape-sugar, 
cane-sugar, lactose, amylodextrin, glycerine, alcohol, aspa- 
ragin, and urea. Inorganic salts not appreciably attracting 
are the chlorides and nitrates of sodium, ammonium, and 
calcium, and also lithium nitrate. 
Of the four free acids which seem to be the most widely 
found in cell-sap, namely malic, oxalic, tartaric and citric, 
only malic acid attracts. 
