66 LECTURES 



which came to be called "rudimentary organs," but 

 more properly known now as "vestigial structures" or 

 organs. As examples of these we may cite the teeth in 

 the upper jaw in the embryos of many of the ruminat- 

 ing animals as in the case of the embryos of our com- 

 mon cattle. These teeth never fully develop, are func- 

 tionless and of absolutely no importance to the animal. 

 Teeth also occur in the jaws of young whales that have a 

 similar history, for as we know iu the adult whale the 

 jaws only support the baleen or whalebone, and the total 

 teeth in them entirely disappear, never having had any 

 physiological importance. 



Quite a long list of similar vestigial structures occur 

 in every man, woman and child among us, and it was 

 utterly impossible to make out the purpose of their being 

 there until biology stepped in to render the proper ex- 

 planation. Among birds we find, in one species or an- 

 other, rudimentary wings incapable of being used in 

 flight, and in most all ordinary birds a vestigial chumb 

 in the hand. Snakes have a rudimentary lung, and 

 rudimentary mammw occur among the males of the 

 mammalia. In some lizards the vestigial limbs and the 

 skeletal arches that support them are entirely concealed 

 from superficial view by the skin covering the body; 

 this is also the case with the hind limbs in a whale. 

 Plants everywhere offer us hundreds of like examples. 

 Plenty of cases of rudimentary and sightless eyes occur 

 in various species, which now pass their existence under- 

 ground. But the name of these structures is legion, and 

 scarcely a living organism exists that offers us not one or 

 more examples, so it is quite out of the question to give 

 the list, in extenso, of them here, and as for that in- 

 stances enough have already been cited. 



Of these vestigial organs, Mr. Darwin has said that: 

 "By whatever steps they may have been degraded into 

 their present useless condition are the record of a former 

 state of things, and have been retained solely through 

 the power of inheritance. We can understand, on the 

 genealogical view of classification, how it is that system- 

 atists, in placing organisms in their proper places in the 

 natural system, have often found rudimentary parts as 

 useful as or even sometimes more useful than parts of 

 higii physiological importance. Rudimentary organs 

 may be compared with the letters in a word, still retained 

 in the spelling but become useless in the pronunciation, 

 but which serve as a clew for its derivation. On the view 

 of descent with modification, we may conclude that the 



