1874^] RESPIRATION OF FRESHWATER FISHES. 317 



diaphragm. It remained for a long time vertically suspended in the 

 water, with the extremity of the snout at the surface, taking in air, 

 which occasionally passed upwards in buhbles from the gill-openings 

 and from the anus. 



On some occasions, on being disturbed, it would rise from the 

 bottom, quickly attain the surface, and almost immediately afterwards 

 discharge a considerable amount of air from the anus. 



Exp. /. — Two specimens of Anabas scande?is* , the Common Climb- 

 ing Perch of India, were placed in a glass jar, and a diaphragm of 

 net fixed at about 1 inch beneath the surface of the water. Almost 

 immediately on being placed in the water the fishes rose and at- 

 tempted to reach the surface. They continued their attempts for 

 about five minutes, striking vigorously against the net ; they then 

 sank down, and died in twelve minutes from the time they were pre- 

 vented from having access to the surface of the water. 



Exp. 8. — A specimen of Trichogaster fasciatus was placed in the 

 same glass ; and immediately after it had been observed to rise to the 

 surface of the water the netted diaphragm was fixed half an inch 

 beneath the surface — at 12 noon. Two minutes afterwards it again 

 attempted to rise, but, being repulsed by the net, swam about, seeking 

 for some means of exit. During the succeeding hour it frequently 

 rose towards the surface and struck violently against the net and the 

 sides of the vessel, the respiration becoming much affected, the gill- 

 covers moving very rapidly. At 3 p.m. the fish lay at the bottom of 

 the jar on its side; at 3.20 p.m. it again attempted to reach the 

 surface, but had lost the power of maintaining its equilibrium, and 

 moved convulsively about with the abdomen upwards; at 3.30 p.m. 

 it lay expiring at the bottom of the jar. 



The net was now removed ; and the fish succeeded by a violent 

 effort in reaching the surface of the water, when it quickly drew in 

 some air and again sank to the bottom. It appeared much revived, 

 but still lay with the abdomen upwards. Soon afterwards it rose 

 again to the surface, and remained suspended vertically in the water 

 with the extremity of the snout at the surface, and continued in this 

 position for some minutes. Again it sank downwards, but appeared 

 better able to maintain its equilibrium. After rising several times 

 to the surface the fish regained completely the power of maintaining 

 its equilibrium, appeared nothing the worse for what it had suffered, 

 and swam about as usual. 



The same experiment was repeated with the same fish on the 

 following morning. It was placed in pure well-aerated water. The 

 same results took place ; and it died in four hours and a quarter. 



Exp. 9. — Placed a specimen of Ophiocej)halus striatus, 1 1 inches 

 long, in the glass jar, and fixed the netted diaphragm 1 inch beneath 

 the surface of the water. After seven minutes the fish became 

 uneasy, and frequently rose towards the surface, but was repulsed by 

 the net. Five minutes afterwards it rushed with great force against 

 the net, burst one of the meshes, and passed through it to the sur- 



* The accessory respiratory organs of this fish are described in ' Owen's 

 'Anatomy of Vertebrates,' vol. i. p. 487. 



