RUDIMENTARY ORGANS. 17 
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 imheritance, 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 Labiatz is explained, if we admit 
that all the plants of this family sprung from one common 
ancestor, provided with five 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 
VOL. I. . Cc 
