GAS DISEASE IN FISHES. 375 



5. The form of the disease caused by the reduction of pressure alone 

 occurs only experimentally, or possibl}' in the case of some deep-sea 

 fishes brought to the surface. 



6. The form of the disease caused by an excess of dissolved air alone 

 is the normal one. Nitrogen excess is more important than oxj'gen 

 excess and can singly cause the disease process. 



7. An excess of about 2 c. c. of nitrogen per liter of water is suffi- 

 cient to cause symptoms. An excess of about 6 c. c, per liter, accom- 

 panied by an excess of about 2 c. c. of oxj^gen, experimentally 

 produced, has been observed in sea water, and kills most adult fishes 

 in a few hours. 



8., A certain increase of pressure will prevent the gas disease where 

 otherwise it would occur, and ma}^ cure affected fishes. It acts by 

 changing the saturation point so that the excess of air no longer exists. 



9. The supersaturated water may be corrected and become harmless 

 by deaeration. This occurs spontaneous!}^ upon standing or may be 

 more quickh^ accomplished by subdividing the water mechanically to 

 olfer a great area of exposure to the atmosphere. This process cor- 

 rects either an excess or a deticiency of air. The water of shallow 

 brooks arising in supersaturated springs or wells is soon corrected by 

 the natural liow. 



BIBLIOGRAPHY. 



1879. KiDDEK, J. H.— The Animal Heat of Fishes. Nature, London, VoL XXI, p. 



156. 

 1884. DiTTM,\R, W. — Composition of Ocean Water. Report on tlie Scientific Eesults 



of the Exploring Voyage of H. M. S. Challenger, Vol. I, Part I. 

 Regnard, p. — Note sur les conditions de la vie dans les profondeurs de la mer. 



Comptes Rendus Societe de Biologie, T. XXXVI, 1884, pp. 164, 187, 



310, 394. 



1895. Foster, jM.— A Text Book of Physiology. Part II. 



1896. CoMEY, A. M. — A Dictionary of Chemical Solubilities. 



Fredericq, L. — Sur la tension des gaz du sang arteriel et la theorie des echanges 

 gazeux de la respiration pulmonaire. Archives de Biologie, T. XIV, pp. 

 105-118. 



1898. GoRHAM, F. P. — Some Physiological Effects of Reduced Pressure on Fish. 



Journal of the Boston Society of Medical Sciences, Vol. Ill, p. 250. 

 Haldane, J. S.— Secretion and Absorption of Gas in the Swimming Bladder. 



Science Progress, Vol. VII, p. 120. 

 Leu'is, Frederic T. — ^The Physiological Effect of Compressed Air. Boston 



INIedical and Surgical Journal, Oct. 6, p. 338. 



1899. Barbour, E. H. — Wells and Windmills in Nebraska. U. S. Geological Survey, 



Water-Supply and Irrigation Paper No. 29. 

 GoRHAM, F. P. — The Gas Bubble Disease in Fishes and its Cause. Bull. U. S. 

 Fish Commission, Vol. XIX, pp. 33-37. 



1900. V>'isxer, J. N.— Report on Battery Station, Havre de Grace, Md., Rept. U. S. 



Fish Commission, p. 50. 



1901. Hammarstex, Olof. — A Text Book of Physiological Chemistrj'. 



1902. Hemi'kl^ Walther. — Methods of Gas Analysis. Translation by L. M. Dennis. 



