236 ANIMAL SKETCHES. CHAI>. 



sweep of my small collecting net I secured some hundreds 

 of these little eels, some of which are now darting to and 

 fro in the patch of sunshine which illumines one side of 

 my aquarium tank. Every now and then one comes to 

 the surface and endeavours to climb the slippery sides of 

 the glass bowl ; no sooner, however, is his tail raised above 

 the water than he slips back again and resumes his rest- 

 less swimming to and fro. Others are lying among the 

 algae at the bottom of the tank with their heads slightly 

 raised, gulping in the sweet, fresh water which is richly 

 oxygenated by the gas-beads which dot the aquatic plants 

 under the influence of the life-giving sunlight. 



Let us remove one of these semi-transparent fishlets and 

 examine him. One now lies before me in the lid of a 

 Fry's cocoa tin. He is just three inches long and no 

 stouter than a steel knitting needle. He could comfort- 

 ably squeeze through the large of this type. His head 

 is somewhat, but not very decidedly, pointed, and his jaws 

 are distinctly underhung. The black, bead-like eyes are 

 strongly marked, and behind them the outline of the 

 brain very fairly developed for a juvenile fish of his 

 inches can be traced within the skull. Between the 

 back of the skull and the delicate pectoral fins the body 

 is somewhat swollen, and pulsates with a fairly regular 

 beat ; and through the transparent walls of the pulsating 

 chambers on either side may be seen four red curved bars, 

 which move in and out with the pulsations, separating as 

 they move out and closing together as they are drawn in. 

 They are the gill-arches which bear the breathing appa- 

 ratus or gills, red with the life-blood which is here being 

 oxygenated and purified. Like all the ordinary fishes, the 

 eel breathes the oxygen dissolved in the water, which is 

 taken in at the mouth, passes through the slits between 

 the gill-arches, and so over the gills in which the blood is 



