EMERGENCY RESPIRATION 



45 



Periophthalmus schlosseri on land.. (Eggert.) 



from a marine existence to a life mainly in moist air. The 

 most specialized is Periophthalmus. Figure 18 shows the mouth 

 and branchial cavity characteristically blown up with air. 

 The gill lamellae have coa- 

 lesced leaving only narrow 

 slits, and the gills are un- 

 suitable for water respira- 

 tion (E. Schottle, 1932). If 

 the spaces can be air-filled 

 they may assist the respira- 

 tion in air. 



When in fresh water the 

 concentration of oxygen be- 

 comes reduced, many fishes 

 and some other water-breath- 

 ing animals will come to the 

 surface, which by diffusion 

 exchange with the atmos- 

 phere will present a micro- 

 stratification with a compar- 

 atively high oxygen tension 

 in the very surface. This 

 reaction takes place in the 

 dragon fly larvae {Aeschna), 

 according to Wallengren f FlG ' 19 ' Aeschna larv * seeking . the 



° ° surface tor emergency respiration. 



(1914), when the oxygen (Wallengren.) 



