574 Butter.—Contributions to our Knowledge of the 
TABLE V. 
Standard solutions of 
potassium nitrate 
) in parts of a mol 
| in grams per cent. 
1 
IO-I 
i 
5‘°5 
1 
2 
inr 
1-0 
ih 
0.5 
TW 
O-1 
Potassium nitrate 
KNO3 
101 
0 
0 
C 
F 
F 
F 
Sodium chloride 
NaCl 
5^5 
0 
0 
C 
F 
F 
F 
Cane sugar 
Ci 2 H m O u 
342 
0 
0 
C 
F 
F 
F 
Glycerine 
C s H 5 (OH) 3 
92 
F 
F 
F 
F 
F 
F 
Alcohol 
c 2 h 6 o 
46 
F 
F 
F 
F 
F 
F 
From the above Table it will be noticed that at the con¬ 
centration mol potassium nitrate, sodium chloride and 
cane-sugar the spermatozoa move forward. The move¬ 
ment is, however, not so rapid as at -gV. At the concentra¬ 
tion yjy- mol movement takes place in the same manner as 
in tap-water alone. At the concentration £ mol the sper¬ 
matozoa are still liberated, but after being set free from 
their mother-cells only move their cilia, and are not capable 1 
of moving forward through the medium. The movement of 
the cilia often lasts a long time. I have watched such move¬ 
ment in 2-05 gm per cent, potassium nitrate for an hour. A 
certain number of spermatozoa liberated at the concentrations 
y'y and -J- mol never move at all. At the concentration 
l mol a few antheridia burst, but no motion of the sperma¬ 
tozoa was observed. 
The spermatozoa were able to move forward in all the 
solutions of glycerine and alcohol tested. The difference in 
the behaviour of the organisms in solutions of these sub¬ 
stances and in solutions of potassium nitrate, sodium chloride 
and sugar, is to be accounted for by the fact that the former 
two substances 2 rapidly penetrate living cell-membranes, 
whereas the latter three are practically excluded from pene¬ 
trating at all. Solutions of alcohol and glycerine do not 
therefore cause the same physical disturbance, namely the 
1 Exceptionally a spermatozoon struggles a very short distance and very slowly 
through the medium. 
2 For literature, see p. 556. 
