116 UNIVERSALITY OF DEGENERATIVE EVOLUTION 



1. Rudimentary organs, signs of a degenerative 



transformation in the organism itself, are 

 either organs which have ceased to be 

 functional, or which have so diminished in 

 importance that their total disappearance 

 would be unattended by any appreciable 

 loss to the organism. In the majority of 

 cases this cessation of function is attended 

 by a corresponding structural decay. 



2. The system of comparing living organisms 



with their presumptive ancestors equally 

 demonstrates the retrogression of certain 

 organs. 



Among the Orobanchacete for instance, parasitic 

 plants derived from normal green plants, no trace 

 of cotyledons is observable from the period of 

 germination. 1 



Among animals, taking the horse as an example, 

 several organs have wholly disappeared. In the 

 genealogy of the horse, which is well known, the 

 earliest ancestor Eohippus, possessed five functional 

 fingers on the fore-feet, and four toes on the hind- 

 feet. The horse still possesses one functional finger 

 and one functional toe, two rudimentary fingers and 

 two rudimentary toes. Two fingers and two toes 

 have entirely disappeared. 



It is hardly necessary to point out that this 

 system of comparison does not demonstrate the 



1 L. Koch, Die Entwickclungsgeschichte der Orobanchen. Heidel- 

 berg, C. Winter, 1887. 



