220 WHALES, PAST AND PRESENT xy, 



exists in different species of whales, show very marked varieties 

 of progress, from a simple comparatively rudimental and im- 

 perfect condition, to what is perhaps the most wonderful 

 example of mechanical adaptation to purpose known in 

 any organic structure. These variations are worth dwelling 

 upon for a few minutes, as they illustrate in an excellent 

 manner the gradual modifications that may take place in 

 an organ, evidently in adaptation to particular requirements, 

 the causation of which can be perfectly explained upon 

 Darwin's principle of natural selection. 



In the rorquals or fin-whales (genus JBalcenoptera, Fig. 1 2, p. 

 198), found in almost all seas, and so well known off our own 

 coasts, the largest blades in an animal 70 feet long do not exceed 

 2 feet in length, including their hairy terminations ; they are in 

 most species of a pale horn colour, and their structure is coarse 

 and inelastic, separating into thick, stiff fibres, so that they are 

 of no value for the ordinary purposes to which whalebone is 

 applied in the arts. These animals feed on fish of considerable 

 size, from herrings up to cod, and for foraging among shoals 

 of these creatures the construction of their mouth and the 

 structure of their baleen is evidently sufficient. This is the 

 type of the earliest known extinct forms of whales, and it has 

 continued to exist, with several slight modifications, to this 

 day, because it has fulfilled one purpose in the economy of 

 nature. Other purposes for which it was not sufficient have 

 been supplied by gradual changes taking place, some of the 

 stages of which are seen in the intermediate conditions still 

 exhibited in the Megaptera and in the Atlantic and southern 

 right whales. Before describing the extreme modifications 

 in the direction of complexity, I may mention, to show the 

 range at present presented in the development of baleen, that 

 there has lately been discovered in the North Pacific a species 

 called by the whalers the Californian grey whale (Eachianectes 

 glawus), which shows the opposite extreme of simplicity. The 

 animal is from 30 to 40 feet in length; the baleen blades are 

 only 182 on each side (according to Scammon) and far apart, 

 very short (the longest being from 14 to 16 inches in length), 

 light brown or nearly white in colour, and still more coarse in 

 grain and inelastic than that of the rorquals. The food of 



