278 Comparative Animal Physiology 



respiration became common. Lung and tracheal breathers have further 

 progressed to permit some to become secondarily aquatic. Various taxic and 

 migratory movements may be traced to oxygen requirements. 



Ventilation movements in invertebrates and vertebrates alike are decidedly 

 influenced by various factors, including temperature, carbon dioxide excess, 

 and oxygen deficiency. Of these, carbon dioxide appears to play the most 

 significant role in respiratory control in the warm-blooded (generally terrestri- 

 al) vertebrates but is of lesser relative importance among lower (aquatic) 

 animals. 



Metabolic adaptations, including the oxygen-deficiency processes of anaer- 

 obic glycolysis, anaerobiosis, accumulation of oxygen debt, carbon dioxide 

 insensitivity, and carbohydrate conversion, have enabled organisms to with- 

 stand severe oxygen stress and likewise have played a major role in the 

 ecological distribution and behavior pattern of these animals. The amount of 

 oxygen required, the minimum tolerable gas tension, and the oxygen utiliza- 

 tion, although subject to modification by activity, age, size, temperature, 

 season, nutrition, and sex, are characteristic for each organism. A survey of 

 respiratory and metabolic adaptations demonstrates remarkably the many 

 interrelations between the fitness of organisms and their environment. 



REFERENCES 



1. Adrian, E. D., }. Physiol. 72:132-151(1931). Insect ganglionic potentials. 



2. Agar, W. E., Anat. Am. 33: 27-30 (1908). Pectoral gills of lungfish. 



3. Alsterberg, G., Umdis Univer. Aarsskr. N. F. Avd. 2, 18:1-176 (1922); ibid. 

 20: 1-77 (1924). Respiration in Tubificidae. 



4. Amberson, W. R., Biol. Bull. 55:79-92 (1928). Oxygen consumption and 

 critical tensions. 



5. Amberson, W. R., Mayerson, H. S., and Scott, W. J., /. Gen. Physiol. 7:171- 

 176 (1924). Oxygen tension and consumption; invertebrates. 



6. Amerling, K., Pfliig. Arch. 121:363-369 (1908). Oxygen sensitivity and age. 



7. Atlas, M., Physiol. Zool. 11:278-291 (1938). Oxygen consumption of frog 

 embryos. 



8. Babak, E., in Winterstein's Handhuch der vergleichenden Physiologie (1921). 

 Jena, G. Fischer. Vol. 1, Part 2, pp. 265-1028. Mechanics of breathing. 



9. Babak, E., and Dedek, B., Pfliig. Arch. 119:483-529 (1907). Respiratory control 

 among lish. 



10. Baker, C. L., ]. Tenn. Acad. Sci. 17:39-51(1942). Air breathing teleosts. 



11. Baker, E. G. S., and Baumberger, J. P., /. Cell. & Comp. Physiol. 17:285-304 

 (1941). Critical oxygen tension; Tetrahymena. 



12. Baldwin, E., Dynamic Aspects of Bio-chemistry (1947). Cambridge Univ. Press. 

 Chap. 4, 15. 



j/l3. Baldwin, F. M., Proc. Iowa Acfld. Sci. 30:173-180(1924). Oxygen consumption 

 in marine animals. 



14. Baldwin, S. P., and Kendeigh, S. C, Sci. Puhl. Cleveland Miis. Nat. Hist. 

 3:1-196(1932). Bird respiration. 



15. Ball, E. G., Ann. Rev. Biochem. 11:1-25 (1942). Biological o.xidation and 

 reduction. 



16. Barach, a. L., Fenn, W. O., Ferris, E. B., and Schmidt, C. F., /. Aviation Med 

 18:73-87 (1947). Pressure breathing. 



17. Barcroft, J., Physiol Rev. 16:103-128 (1935). Fetal respiration. 



18. Barcroft, J., and Barcroft, H., Proc. Roy. Soc. Lond. B., 96:2842 (1924). 

 Pulmonary respiration. 



19. Barnes, T. C, Textbook of Physiology (1937). Philadelphia, Blakiston. Chap. 

 13. 



