30 DEGENERATION : I 



against a piece of wood, and takes to a perfectly 

 fixed, immobile state of life (Fig. 10). The upper 

 figures represent the Nauplius stage of animals closely 

 resembling the Barnacle ; the lower figures show the 

 transformation of the Nauplius into the young 

 Barnacle. Its organs of touch and of sight atrophy, 

 its leo^s lose their locomotor function, and are 

 simply used for bringing floating particles to the 

 orifice of the stomach ; so that an eminent naturalist 

 has compared one of these animals to a man standing 

 on his head and kicking his food into his mouth. 



Were it not for the recapitulative phases in the 

 development of the Barnacle, we may doubt whether 

 naturalists would ever have guessed that it was a 

 degenerate Crustacean. It was, in fact, for a long- 

 time regarded as quite remote from them, and placed 

 among the snails and oysters ; its true nature was 

 only admitted when the young form was discovered. 



Other parasitic organisms, which exhibit extreme 

 degeneration as compared with their free-living rela- 

 tives, might be cited and figured in profusion, did our 

 limits permit. Very noteworthy are the degenerate 

 Spiders — the mites, leading to still more degenerate 

 forms, the Linguatulse.^ 



We have two of these represented in Figs. 1 1 and 

 12. The one (Fig. 11), as compared with a spider, is 



1 I have, since the above was written, applied the principle of 

 degeneration to the explanation of the living representatives of the 

 group Arachnida, and shewn that the King Crab (Limulus) is the 

 nearest representative of the ancestors of scorjoions, spiders, and mites, 

 and in fact must be classed with them. Professor Claus of Vienna has, 

 some years later, adopted similar views. December 1889. 



