146 THE WAYS OF BREATHING 



herring family and contrary to the experience 

 of the common herring. 



The Siluroid fish Arius falcarius, of which 

 mention has been made above, exhibits great 

 viability out of water. A large female, 14^ 

 inches long, which had been caught by a hook 

 but had not been injured, lived for nearly five 

 hours out of water, breathing regularly by 

 mouth and gills, without accessory structures, 

 closing the gill - cavity behind by the opercular 

 membrane. After it had been out of water for 

 about an hour I counted 80 buccal respirations 

 to the minute, the opercular membrane beating 

 time with the mouth but remaining quite closed 

 behind. After two hours there were 70 respira- 

 tions to the minute ; and after three hours 60 

 feebler respirations, the opercular membrane now 

 commencing to gape behind. At the end of 

 the experiment the heart was removed and con- 

 tinued beating outside the body. This example 

 shows that the phenomenon of viability out of 

 water is something apart from the possession 

 of accessory branchial organs. 



Another Siluroid fish, Plotosus canitis, exhibits 

 similar viability, living from early morning until 

 afternoon (over six hours) out of water, the gills 

 remaining quite fresh to the end. In this case 

 periodical expirations took place through the 

 gill-opening ; every now and then the opercular 

 membrane was raised several times in succession, 



