EFFECTS OF PULP MILL POLLUTION ON OYSTEES 
143 
on October 23 and until the end of the experiment, specimen No. 1 averaged 6.76 
while specimen No. 2 averaged 7.06 hours per day open. For a comparable period of 
time (October 22 to November 23) 
control No. 3 averaged 19.86, while 
No. 4 averaged 16.44 hours per day 
open. Even the controls show a 
more or less progressive lowering of 
the curves. This was due, as in the 
case of experiments Nos. 8 and 9, to s 10 
temperature fluctuation. During £ 6 1 
the tests the average daily water 
temperature fell gradually from 2 - 
about 13 ° C. at the beginning to 13 i4 | 5 | 6 n ie 19 20 21 22 23 24 25 26 27 28 29 30 31 1 
about 5° C. at the end of the series. December jan. 
fry. • i i , • , n Figure 23.— Graph showing records of the two specimens in experiment 
I JllS, however, does not interfere No, 8 (0.44 part per 1,000). Compare with the controls (fig. 22 ) and 
with the well warranted conclusion the temperature record (fig. 24 ) 
that the presence of the liquor was the cause of the experimental oysters remaining 
open less, for the controls were open more than twice as much. 
Experiment No. 8 ( 0.83 parts 
per thousand ). — The water rate was 
300 cubic centimeters per minute 
and that of liquor (1:19) was 5.13 
cubic centimeters per minute. The 
pH of the solution varied between 
7.0 and 7.5. The results compare 
favorably with those obtained in ex- 
periment No. 2 and show a definite 
reduction in number of hours per 
day open. (Fig. 27.) During the 
13 14 15 16 17 IB 19 20 21 22 23 24 25 26 27 26 29 3D 31 
DECEMBER JAN. 
Figure 24 .— Graph showing average daily temperature of the water in experimental period specimen No. 5 
experiments Nos 
ing other periods it 
panied by changes in the behavior of the oysters (figs. 21 to 23) 
i. At times the water was heated, while dur- ion j • _ „ n a r. 
cold. These temperature changes are accom- averaged 8.51 and specimen 6, 9.49 
hours per day open, as compared 
with controls Nos. 3 and 4, which remained open 16.44 and 19.86 hours per day, re- 
spectively. Comparison of the record of specimen No. 5 with the records of other 
Figure 25.— Records of the oysters used in experiment No. 2 (0.5 part per 1,000). As com- 
pared with the controls (fig. 26), these specimens remained closed a large proportion of the 
time 
oysters which died under treatment (figs. 8, 10, 11, 13, 15, 17, 18) suggests that this 
specimen, after having remained closed for a long time, was opening slowly to die. 
