THE GAS DISEASE IN FISPIES. 



By M. C. Marsh, Assistant, Bureau of Fisheries, and F. P. Gorham, Associate Professor 

 of Biology, Brown Unifersity. 



INTRODUCTION. 



The pathologic symptoms and changes which affect fishes and some 

 other aquatic animals, and are here grouped as a unity under the 

 general term "gas disease", do not include all abnormal manifestations 

 of gas or symptoms involving gas. In the literature of the pathology 

 of the lower animals gas disease does not appear to be recognized 

 definitive!}^, though some of the numerous references to gaseous symp- 

 toms, and particularly to the so-called "pop-eye" in fishes, doubtless 

 apply to the disease as here discussed and limited. In cattle and other 

 mammals certain bacterial diseases are accompanied b}^ evolution of 

 gas within the tissues. 



The gas disease of aquatic animals was first observed and recognized 

 among fishes in sea water at the station of the Bureau of Fisheries at 

 Woods Hole, Mass. It has been observed also at other stations, at the 

 New York Aquarium, and among fresh-water fishes, and it has without 

 much doubt occurred at private establishments. At Woods Hole it is 

 known to have progressed for several years. 



In general terms the cause of the gas disease lies in the relation of 

 the amount of air dissolved in the water in which the affected fishes 

 live to temperature and pressure. An understanding of this relation 

 will follow a consideration of the laws of solubility of gases in water 

 and particularly of the gases which constitute the atmosphere. 



SOLUBILITY OF GASES IN WATER. 



The amount of a given gas which pure water will dissolve depends 

 upon temperature and pressure and upon the sohibility of the gas. 

 Under increased pressure the capacity of water for holding anj' gas is 

 increased, while at an increased temperature this capacity is dimin- 

 ished. The coefficient of solubility varies widely for the difi'erent 

 gases. Oxygen and nitrogen, which chiefly make up the atmosphere, 

 are but slightly soluble in water, while carbon dioxid, which con- 



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