200 ANAEROBIOSIS 



invertebrates such as intestinal worms and mud-dwelling organisms probably live 

 without free oxygen owing to the presence of numerous micro-organisms which reduce 

 the oxygen supply practically to zero, and raised the question as to how the muscles 

 of such organisms secure their energy. 



According to Weinland,' intestinal worms effect a true fermentative process under 

 anaerobic conditions, as foUows: 



4C6H,.06-9CO.-f sQH.oO.+gH, . 



Piitter^ kept leeches alive ten days without oxygen. During the interval hydrogen was 

 set free with a primary rise in CO2 output followed by a fall. 



Packard^ showed that the resistance of Fundulus embryos could be increased either by 

 the injection of sodium bicarbonate or of certain carbohydrates. There is a possible analogy 

 in Packard's reasoning to that of Pasteur which suggests that carbohydrates probably 

 present in the organic slimes at the bottom of lakes make anaerobic life among some animals 

 as well as bacteria possible there. 



Juday^ has noted that while the water from near the bottom of a lake may contain 

 considerable oxygen during the winter months, in summer two factors operate to reduce the 

 oxygen content to so low a value that it cannot be determined, namely, first, decaying 

 organic matter, and second, lack of convection currents due to the warm and therefore lighter 

 layer of water at the surface. In the slime collected from Lake Mendota, Wisconsin, various 

 protozoa as well as higher invertebrates such as rotifers, worms, molluscs, crustaceae, and 

 insect larvae were found frequently. None of the protozoans pumped from the bottom into 

 anaerobic containers was in any way abnormal or inactive. Juday^ recently recorded an 

 obligately anaerobic ciliate resembling Enchelys. On the other hand, according to Juday 

 and Wagner, "No fish has ever been found which leads either an active or passive life in 

 water that is free from dissolved oxygen."* Therefore, while the depths of a given lake may 

 present suitable temperature conditions for the implantation of trout, and the surface layers 

 an ample oxygen and food supply, the separation of these factors by stratification of the 

 water during the summer months may prevent stocking and even account for the death of 

 many fish in a well-stocked lake. Birge and Juday^ state that most fish require an oxygen 

 content in the water of at least 2 cc. per liter (N.T.P.), whereas many protozoa and inverte- 

 brates live in water containing less than o.i cc. oxygen per liter. 



In the tissues of higher animals many of the processes may be considered as essentially 

 anaerobic. Bayliss^ referred to lactic acid as the product of anaerobic change in frog muscle, 

 CO2 as that of aerobic change, and Shelford has pointed out that "high respiratory quotients 

 of various animals are further evidence of anaerobic respiration. "« 



' Weinland, E.: Z/5c/?r./. 5/0/., 42, 55. i9oi;43, 86. 1902; 45, 113 and 517. 1904148,87. 1906. 

 ^ Putter, A.: Zlschr. allgem. Physiol., 6, 217. 1907; 7, 16. 1907. 

 3 Packard, W. H.: Am. J. Physiol., 15, 30. 1905; 18, 164. 1907. 

 ^ Juday, C: Tr. Wisconsin Acad. Sc, 16, 10. 1909. 

 5 Juday, C: Biol. Bull., 36, 92. 1919. 



* Juday, C, and Wagner: Tr. Wisconsin Acad. Sc, 16, 17. 1909. 

 7 Birge, E. A., and Juday, C: ibid., p. i. 1908. 



' Bayliss, W. M.: Principles of General Physiology (4th ed.). London: Longmans & Co., 1924. 

 'Shelford, V. E.: chap, ii in Ward, H. B., and Whipple, G. C: Fresh Water Biology. New York: 

 Wiley, 1918. 



