384
J
.22kw
.20.I 8,I 6KJELL JOHANSEN
A
A
A
A
.28 ,
.24
b
,
-
Qw Ez 50L---,- 25
10
20
30
40
50
60
Time from breath (minutes)
Fig. 9. Time course of changes in 0 2 tension, CO? tension, and the gas exchange
ratio ( R E ) inside the lung of Protopterus between successive air breaths. From
Lenfant and Johansen (1968).
hr. Similarly, Berg and Steen (1965), working on the common eel, reported on 0, uptake in air half of the value measured in water. A
different pattern is evident in Protopterus during air exposure. A normal
level of 0, uptake was maintained when rebreathing air until the ambient
0, tension had fallen to 80 mm Hg and CO, tension had risen to 3540
mm Hg.
Figure 8 shows the rate of change of gas composition inside airbreathing organs of a number of fishes based on samples obtained when
the animals were resting in well-aerated water. The rate of 0, absorption
in the obligate air breathers is conspicuously higher than in the fishes
J
.22kw
.20.I 8,I 6KJELL JOHANSEN
A
A
A
A
.28 ,
.24
b
,
-
Qw Ez 50L---,- 25
10
20
30
40
50
60
Time from breath (minutes)
Fig. 9. Time course of changes in 0 2 tension, CO? tension, and the gas exchange
ratio ( R E ) inside the lung of Protopterus between successive air breaths. From
Lenfant and Johansen (1968).
hr. Similarly, Berg and Steen (1965), working on the common eel, reported on 0, uptake in air half of the value measured in water. A
different pattern is evident in Protopterus during air exposure. A normal
level of 0, uptake was maintained when rebreathing air until the ambient
0, tension had fallen to 80 mm Hg and CO, tension had risen to 3540
mm Hg.
Figure 8 shows the rate of change of gas composition inside airbreathing organs of a number of fishes based on samples obtained when
the animals were resting in well-aerated water. The rate of 0, absorption
in the obligate air breathers is conspicuously higher than in the fishes