A DRAINED FISHPOND. 



biologists now generally allow, we have the 

 first faint beginnings of the evolution of 

 lungs and the habit of air-breathing. Nay, 

 more, terrestrial life itself, as a whole, 

 depends in the last resort upon just such 

 first feeble gaspings and gulpings. For 

 lungs are nothing more, anatomically speak- 

 ing, than developed swim-bladders, con- 

 nected by a definite passage with the 

 external air, and provided with a more 

 or less perfect muscular mechanism for 

 inhaling and expelling it. 



In most fish, and in all the rudest types, 

 the swim-bladder is merely a float or balloon, 

 which can be filled with air, and compressed 

 or expanded, so as to make the animal rise 

 or sink at pleasure. But many fish exist 

 in tropical ponds and shallow swamps to 

 whom what has happened artificially to 

 the carp in my friend's ornamental water 

 happens naturally every dry season ; the 

 marshy sheets in which they live evaporate 

 altogether, and they are therefore compelled 

 225 Q 



