SUMMARY . 273 



be further reduced or absorbed for the sake of econo- 

 mizing nutriment. 



Finally, as rudimentary organs, 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 inheri- 

 tance — we can understand, on the genealogical view of 

 classification, how it is that systematists, 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 high physiological 

 importance. Rudimentarj^ 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 existence of 

 organs in a rudimentary, imperfect, and useless condition, 

 or quite aborted, far from presenting a strange difficulty, 

 as they assuredly do on the old doctrine of creation, 

 might even have been anticipated in accordance with the 

 views here explained. 



Summary 



In this chapter I have attempted to show that the 

 arrangement of all organic beings throughout all time in 

 groups under groups — that the nature of the relationships 

 by which all living and extinct organisms are united by 

 complex, radiating, and circuitous lines of affinities into a 

 few grand classes — the rules followed and the difficulties 

 encountered by naturalists in their classifications — ^the 

 value set upon characters, if constant and prevalent, 

 whether of high or of the most trifling importance, or, 



