408
KJELL JOHANSEN
consequence to gas exchange, and no apparent tendency for a preferential distribution of blood from the pulmonary vein to the systemic
arteries is apparent. Exposure to hypoxic water evokes an active use of
the lung and results in a clear preferential passage of blood from the
lung to the anterior branchial arteries which carry the major portion
of the blood to the dorsal aorta. One analysis showed that more than 83%
blood from the pulmonary vein passes this way, whereas recirculation
of systemic venous blood to the anterior arches was reduced to about 16%.
Lepidosiren and Protopterus are much more dependent on air breathing and show a consistent gradient of 0, tension between blood in
systemic and pulmonary arteries. This gradient reflects the degree of
preferential perfusion which increases with an increased rate of air
breathing (Table 111). In Protopterus (Johansen et al., 1968) the proportion of blood conveyed to the systemic arteries from the pulmonary
circuit could be as high as 95% shortly after a breath and decline to about
65% just prior to the next air breath. The factors important in the control
of the preferential passage of blood are hence also coupled to the
breathing rhythm.
REFERENCES
Barrel], J. (1916). Influence of Silurian-devonian climates on the rise of air-breathing
vertebrates. Bull. Geol. SOC. Am. 27, 387436.
Berg, T., and Steen, J. B. (1965). Physiological mechanisms for aerial respiration
in the eel. Comp. Biochem. Physiol. 15, 46-84.
Bishop, I. R., and Foxon, G. E. H. ( 1968). The mechanism of breathing in the South
American lungfish, Lepidosiren purudoxa; a radiological study. J. Zool., Lond.
154, 263-271.
Boker, H. (1933). Uber einige neue Organe bei luftatmenden Fischen und im Uterus
der Anakonda. Anut. Anz. 76, 118-155.
Budgett, J. S. (1900). Observations on Polypterus and Protopterus. Proc. Cambridge
Phil. SOC. 10, 236.
Calugareanu, D. (1907). Die Darmatumung von Cobitis fossilis. 11. Mitteilung: Uber
den Gaswechsel. Arch. Ges. Physiol. 120, 425-450.
Carter, G . S. (1935). Reports of the Cambridge expedition to British Guiana 1933.
Respiratory adaptations of the fishes of the forest waters, with descriptions of
the accessory respiratory organs of Electrophorus electricus L. and Plecostomus
plecostomus L. J. Linnean SOC. London 39, 219-233.
Carter, G. S. (1951). “Animal Evolution.” Sidgwick & Jackson, London.
Carter, G. S., and Beadle, L. C. (1931a). The fauna of the swamps of the Paraguayan
Chaco in relation to its environment. I. Physico-chemical nature of the environment. J. Linneun SOC. London 37, 205-258.
Carter, G. S., and Beadle, L. C. (1931b). The fauna of the swamps of the Paraguayan
Chaco in relation to its environment. 11. Respiratory adaptations in the fishes.
J. Linnean SOC. London 37, 327-366.
Cunningham, J. T. (1934). Experiments on the interchange of oxygen and carbon
dioxide between the skin of Lepidosiren and the surrounding water, and the
probable emission of oxygen by the male Symbranchus. Proc. 2001. SOC. London
875-887.
KJELL JOHANSEN
consequence to gas exchange, and no apparent tendency for a preferential distribution of blood from the pulmonary vein to the systemic
arteries is apparent. Exposure to hypoxic water evokes an active use of
the lung and results in a clear preferential passage of blood from the
lung to the anterior branchial arteries which carry the major portion
of the blood to the dorsal aorta. One analysis showed that more than 83%
blood from the pulmonary vein passes this way, whereas recirculation
of systemic venous blood to the anterior arches was reduced to about 16%.
Lepidosiren and Protopterus are much more dependent on air breathing and show a consistent gradient of 0, tension between blood in
systemic and pulmonary arteries. This gradient reflects the degree of
preferential perfusion which increases with an increased rate of air
breathing (Table 111). In Protopterus (Johansen et al., 1968) the proportion of blood conveyed to the systemic arteries from the pulmonary
circuit could be as high as 95% shortly after a breath and decline to about
65% just prior to the next air breath. The factors important in the control
of the preferential passage of blood are hence also coupled to the
breathing rhythm.
REFERENCES
Barrel], J. (1916). Influence of Silurian-devonian climates on the rise of air-breathing
vertebrates. Bull. Geol. SOC. Am. 27, 387436.
Berg, T., and Steen, J. B. (1965). Physiological mechanisms for aerial respiration
in the eel. Comp. Biochem. Physiol. 15, 46-84.
Bishop, I. R., and Foxon, G. E. H. ( 1968). The mechanism of breathing in the South
American lungfish, Lepidosiren purudoxa; a radiological study. J. Zool., Lond.
154, 263-271.
Boker, H. (1933). Uber einige neue Organe bei luftatmenden Fischen und im Uterus
der Anakonda. Anut. Anz. 76, 118-155.
Budgett, J. S. (1900). Observations on Polypterus and Protopterus. Proc. Cambridge
Phil. SOC. 10, 236.
Calugareanu, D. (1907). Die Darmatumung von Cobitis fossilis. 11. Mitteilung: Uber
den Gaswechsel. Arch. Ges. Physiol. 120, 425-450.
Carter, G . S. (1935). Reports of the Cambridge expedition to British Guiana 1933.
Respiratory adaptations of the fishes of the forest waters, with descriptions of
the accessory respiratory organs of Electrophorus electricus L. and Plecostomus
plecostomus L. J. Linnean SOC. London 39, 219-233.
Carter, G. S. (1951). “Animal Evolution.” Sidgwick & Jackson, London.
Carter, G. S., and Beadle, L. C. (1931a). The fauna of the swamps of the Paraguayan
Chaco in relation to its environment. I. Physico-chemical nature of the environment. J. Linneun SOC. London 37, 205-258.
Carter, G. S., and Beadle, L. C. (1931b). The fauna of the swamps of the Paraguayan
Chaco in relation to its environment. 11. Respiratory adaptations in the fishes.
J. Linnean SOC. London 37, 327-366.
Cunningham, J. T. (1934). Experiments on the interchange of oxygen and carbon
dioxide between the skin of Lepidosiren and the surrounding water, and the
probable emission of oxygen by the male Symbranchus. Proc. 2001. SOC. London
875-887.