RUDIMENTARY ORGANS. 



17 



originated through modifications of those originally adaptive 

 organs which bore within them the elements of continuous 

 and extensive gradual transformation.^ 



This inference includes another : That all the structural 

 peculiaritiM of animals are true organs which must subserve 

 some function and can never be mere useless ornaments. 

 Otherwise, from the Darwinian point of view — which, as I have 

 said, I accept as a standard — it would be quite unintelligible 

 how wholly useless portions of the body could have been in- 

 herited and modified through a long series of divergent descen- 

 dants from the parent form. If it could be strikingly shown that 

 organs actually exist which are of no physiological use to the 



Fig. 7.— Skull of female Dugong ; the colossal tusks in the upper jaw never pierce the 

 thick fleshy lip, although they continue to grow with the jaw. a, the root of the tusk; 

 6, the point. 



possessors, but which determine the types of form in whole 

 Classes, Orders, or Families, then the conclusion would seem 

 inevitable that these functionless organs have been formed in 

 accordance with some transcendental law (or plan) of develop- 

 ment. 



Now it is sometimes asserted, oftener, it is true, by botanists 

 than by zoologists, that such functionless organs do in fact 

 exist. I do not here allude to rudimentary organs ; * for although 

 these appear in sundry groups of animals to be in fact devoid 

 of any recognisable function, they are derived, no doubt by 

 degeneration, from true organs whose functions are conspicuous 

 Ln other animals. The best example known to me of such 

 rudimentary organs is ofiered by the female Dugong {Halicore 



