RUDIMENTARY ORGANS. I 7 



ance of such structures as an entirely natural process, arising 

 from the disuse of the organs. 



By adaptation to special conditions of life, the formerly 

 active and really working organs have gradually ceased 

 to be used or employed. In consequence of their not being 

 exercised they have become more and more imperfect, but 

 in spite of this have always been handed down from one 

 generation to another by inheritance, until at last they 

 vanish partially or entirely. Now, if we admit that all 

 the vertebrate animals mentioned above are derived from 

 one common ancestor, possessing two seeing eyes and two 

 well developed pairs of legs, the different stages of suppres- 

 sion and degeneration of these organs are easily accounted 

 for in such of the descendants as could no longer use them. 

 In like manner the various stages of suppression of the 

 stamens, originally existing to the number of five (in the 

 flower-bud), among the Labiatge is explained, if we admit 

 tliat all the plants of this family sprung from one common 

 ancestor, provided with ^ve stamens. 



I have here spoken somewhat fully of the phenomena of 

 rudimentary organs, because they are of the utmost general 

 importance, and because they lead us to the great, general, 

 and fundamental questions in philosophy and natural 

 science, for the solution of which the Theory of Descent 

 has now become the indispensable guide. As soon, in fact, 

 as, according to this theory, we acknowledge the exclusive 

 activity of physico-chemical causes in living (organic) 

 bodies, as well as in so-called inanimate (inorganic) nature, 

 we concede exclusive dominion to that view of the uni- 

 verse, which we may designate as the mechanical, and 

 which is opposed to the teleological conception. If we 



