WHALES AND THEIR NEIGHBORS. 243 



literal flood of waters streams out of the sides of the mouth, the " sea- 

 butterflies" are strained off therefrom, the savory morsels being re- 

 tained by the fringed edges of the baleen-plates, and thereafter duly 

 swallowed as food. 



An interesting speculation yet remains, however, regarding the 

 origin and first development of these peculiar whalebone-structures. 

 Advocates of the doctrine which assumes that animal forms and their 

 belongings arise by gradual modifications of preexistent animals may 

 be reasonably asked to explain the origin of the baleen-plates of the 

 whales. Let us briefly hear what Mr. Darwin, as the spokesman of 

 the party, has to say in reply to such an inquiry. Quoting a remark 

 of an opponent regarding the whalebone, Mr. Darwin says, if the 

 baleen " ' had once attained such a size and development as to be at 

 all useful, then its preservation and augmentation within serviceable 

 limits would be promoted by natural selection alone. But how to 

 obtain the beginning of such useful development ? ' In answer," con- 

 tinues Mr. Darwin (in his own words), "it may be asked, why should 

 not the early progenitors of the whales with baleen have possessed 

 a mouth constructed something like the lamellated beak of a duck. 

 Ducks, like whales, subsist by sifting the mud and water ; and the 

 family (of ducks) has sometimes been called Criblatores, or sifters." 

 Mr. Darwin's reference to the duck's bill is peculiarly happy. The 

 edges of the beak in these birds are fringed with a beautiful series of 

 horny plates named lamellce, which serve as a straining apparatus as 

 the birds grope for their food amid the mud of ponds and rivers. 

 These plates are richly supplied with nervous filaments, and doubtless 

 also some as organs of touch. Mr. Darwin is careful to add that he 

 hopes he may not " be misconstrued into saying that the progenitors 

 of whales did actually possess mouths lamellated like the beak of a 

 duck. I only wish to show," he continues, " that this is not incredible, 

 and that the immense plates of baleen in the Greenland whale might 

 have been developed from such lamella? by finely graduated steps, each . 

 of service to its possessor." 



In these last words, which we have italicized, lies the strength of 

 Mr. Darwin's hypothesis. Nature will preserve and develop useful 

 structures alone, and will leave the useless and unneeded to perish 

 and decay. This, indeed, is the keynote of natural selection. Mr. 

 Darwin next proceeds to examine in detail the plates and lamella? in 

 the bill of a shoveler duck. He describes the horny plates, one hun- 

 dred and eighty-eight in number, which " arise from the palate, and 

 are attached by flexible membrane to the sides of the mandible." He 

 further notes that these plates " in several respects resemble the plates 

 of baleen in the mouth of a whale." If the head of a shoveler duck 

 were made as long as the head of a species of whale in which the 

 baleen-plates are only nine inches long, the duck's lamella? would be 

 six inches in length. The head of the shoveler is about one eighteenth 



