216 THE THEORY OF EVOLUTION 



condition of the hinder limbs, but in some forms they 

 can still be used (by pushing) for locomotion. 1 Rudi- 

 ments are also those temporary teeth which appear to 

 fulfil no function, which we note in young whales, in 

 bird embryos or young birds ; also the temporary and 

 defectively formed wing stage of the Termitoxenia, a 

 termitophil fly (see p. 201). 



Conclusion from (1). 



The actual points deduced from the facts of embryo- 

 geny all lead to the conclusion : That we obtain manifold 

 information regarding the former conditions of organisms 

 but none at all regarding the origin of the types to 

 which they belong. 



If the nauplius stage of the Lepas species really shows 

 anything, that arises because there is ascribed to the 

 type of the lower Crabs also a typical embryonic 

 development. The Lepas were therefore formerly free- 

 living Cirripedia, which is seen by the still unaltered 

 remainder of the ontogeny and the still recognizable 

 crab characters of the adult form. 



The Sole was really a fish when it assumed the prone 

 mode of life, the Termitoxenia a fly when it became 

 a termite guest, the Whale a pure mammal when it 

 ' went into the water/ etc. 



How Flies, Soles, Crabs, Mammals have phylogene- 

 tically arisen none of the examples show us. 



1 The front extremities are changed into rudders (fins) in Whales and 

 Seals, but the internal skeleton is still fairly that of the quadrupedal 

 Mammalia. They show thus still more of a positive adaptation. 



