210 
PACIFIC SCIENCE, VoL VIII, April, 1954 
was sufficient to equilibrate the oxygen con- 
sumption in the new medium. This method 
also precluded the possibility of an accumula- 
tion of excretions which might affect the 
results of the Winkler titration. 
The animals could move in their containers, 
but usually they very soon became inactive 
and quiet. However, inasmuch as they were 
not artificially immobilized and did move now 
and then, certain fluctuations did appear in 
the oxygen consumption. This condition was 
included because it is known (Jordan and 
Guittart, 1938) that artificial immobilization 
markedly affects the rate of oxygen consump- 
tion. The results of experiments with animals, 
which for some reason or other remained 
restless, were discarded because their oxygen 
consumption was very irregular, as could be 
expected. 
The percentage of oxygen in the water in 
the carboy was varied by bubbling nitrogen 
through it for varying periods of time or by 
adding normal sea water to oxygen- deficient 
water. As the present investigation was con- 
cerned with the effect of varying oxygen ten- 
sions on the oxygen consumption at normal 
temperatures and as no method of maintain- 
ing the temperature at a constant room tem- 
perature was available, no special provisions 
were made to keep the temperature at a con- 
stant level throughout all experiments. How- 
ever, the large carboys (5-gallon capacity) 
insured a comparatively constant temperature 
during a whole experiment, the greatest dif- 
ference encountered being 0.5°C. between 
start and finish. 
Several attempts were made to count the 
number of beats per minute of the scaphog- 
nathites and pleopods. At the normal high 
temperature their movements were so quick 
and the rhythm often so irregular (especially 
at lower oxygen tensions) that it was impos- 
sible to obtain satisfactory counts. However, 
it was sometimes possible to observe an in- 
crease or decrease of the rate of the beats. 
Prior to each experiment the animals were 
starved for 24 hours. 
EXPERIMENTS 
The results of the determinations of the 
oxygen content of in- and outflowing water 
are presented in Table 1, which also includes 
the weight of each animal and the temperature 
of the water. The percentage of oxygen con- 
sumed by the animals as a function of oxygen 
present in the inflowing water has been 
computed. 
TABLE 1 
The Percentage of Oxygen Consumed from 
Flowing Water of Varied Oxygen Concen- 
tration BY Several Species of Crustacea 
SPECIES 
CC. OF 02 PER 
LITER 
PERCENTAGE 
OF OXYGEN 
■ CONSUMED 
Inflow 
Outflow 
Pseudo zius caystrus 
6.24 
6.08 
2.6 
Weight 
6.24 
6.06 
2.9 
3 grams 
6.09 
5.93 
2.6 
Temperature 
5.28 
5.18 
1.9 
27.5-27.8°C. 
4.38 
4.26 
2.7 
4.38 
4.23 
3.4 
4.38 
4.20 
4.1 
2.88 
2.83 
1.7 
2.88 
2.84 
1.4 
2.59 
2.42 
6.6 
2.17 
1.99 
8.3 
1.67 
1.57 
6.0 
1.67 
1.57 
6.0 
1.27 
1.18 
7.1 
1.27 
1.14 
10.2 
1.2T 
1.11 
8.3 
1.18 
1.13 
4.2 
1.18 
1.13 
4.2 
Weight 
6.18 
6.01 
2.8 
2.9 grams 
6.12 
5.97 
2.5 
Temperature 
6.12 
5.98 
2.6 
26.6-27.0°C. 
5.61 
5.50 
2.3 
4.40 
4.31 
2.1 
4.40 
4.29 
2.5 
3.83 
3.76 
1.9 
3.51 
3.46 
1.4 
2.90 
2.86 
1.4 
2.63 
2.48 
5.7 
2.08 
1.93 
7.0 
1.80 
1.66 
7.8 
1.59 
1.46 
8.2 
1.31 
1.19 
9.1 
1.31 
1.20 
8.5 
1.12 
1.08 
3.6 
1.12 
1.07 
4.5 
1.12 
1.07 
4.5 
