Life of the Waters 373 



water is forced out through the baleen sieves, while the little 

 animals it contains are held and then swallowed by the whale. 

 The mouth of a whalebone whale is a wonderfully efficient 

 mechanism. Were the whalebone stiff and inelastic, retain- 

 ing a fixed position in the mouth of the whale, when the 

 mouth was opened there would be left a wide space for the 

 escape of the water between the strainer and the lower jaw. 

 But the plates are both pliable and elastic folding backward 

 in the mouth when the jaws are closed and springing into 

 position when these are opened "like a bent bow," thus 

 closing completely the mouth opening. But the tips of the 

 plates are thin and easily bent, and were they not protected 

 in some way might be bent outward by the force of the water 

 when the jaws are closed, allowing some of its contents to 

 escape. To guard against such a mishap Nature has pro- 

 vided the whale with a large lower lip, which overlaps the 

 tips of the plates and holds them in place. 



JAWS OF WHALEBONE WHALE 

 From Sedgwick after Cuvier in ( ' Eegne Animal. ' ' 



Even man has tried the plankton of the sea and found it 

 good, as testified by no less a personage than the Prince of 

 Monaco himself, who found that the plankton copepods, when 

 roasted in butter, made very good patties. 



About thirty years ago it occurred to the German zoologist, 

 Hensen, to study the productivity of the sea as a source of 

 human wealth, much as one would study the productivity of 

 the land. Hensen thought of this productivity in terms of 

 the smaller forms (chiefly microscopic) of plant and animal 

 life, which constitute the food of fish, and which he named 

 plankton from the Greek word plcmktos, wandering. In order 

 to study its abundance, he constructed a net which is known 

 from its inventor as the Hensen net. This consists of an 

 inverted canvas half cone at the top supported by two. rings, 



