THE GAS DISEASE IN FISHES. 
By M. C. Marsnu, Assistant, Bureau of Fisheries, and F. P. GornHAmM, Associate Professor 
of Biology, Brown University. 
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 ‘‘ gus 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 
definitively, 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 by 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 solubility of the gas. 
Under increased pressure the capacity of water for holding any gas is 
increased, while at an increased temperature this capacity is dimin- 
ished. The coeflicient of solubility varies widely for the different 
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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