FUNCTIONS OF SWIMBLADDER OF FISHES. 



An attempt was made to study the normal composition of the 

 gases of the swimbladder of several species of fishes under as 

 nearly natural conditions as could be obtained. Fishes were 

 caught in gill nests and traps and were immediately conveyed and 

 transferred to a wire cage sunk near the surface of the water in 

 Lake Mendota. The location of the cage was previously tested 

 for its suitability. The fishes were left in this cage from 48 

 to 72 hours. Samples of air content of the swimbladder were 

 then taken by methods already described. The amounts of 

 dissolved gases, temperature, and depth, were recorded at the 

 time the samples were taken. The results are summarized in 



Tables I. and II. 



TABLE I. 



NORMAL PERCENTAGES OF THE GASES OF THE SWIMBLADDER OF PERCH AFTER 

 BEING KEPT IN A WIRE CAGE FOR 72 HOURS IN LAKE MENDOTA. 



SEPTEMBER, 1921. 



