36 ORGANIC DEPENDENCE AND DISEASE 



basket (Euplectella) imprisons a crab in its interior behind 

 the bars it throws across its aperture but feeds it with 

 ever changing water currents ; worms and anthozoan corals 

 grow together, with the tubes of the former surrounded by 

 the cells of the latter, both sweeping the water currents 

 for food which may go to either mouth; dead snail shells 

 in which hermit crabs have taken residence are often beset 

 with sea anemones (Sagartia and Adamsia) whose stinging 

 cells may scare away the enemies of the crab, while the crab 

 favors the fixed anemones by moving his establishment 

 from place to place, thus to new feeding grounds. 



All these conditions seem on the surface entirely harm- 

 less or positively advantageous to all parties involved ; that 

 is, advantageous in the sense that they make life easier, 

 less arduous, discourage activity and perfect adaptation. 



The general effect of all symbiotic conditions is degenera- 

 tive. They themselves arise from degenerate tendencies 

 and could not exist save that degeneration had already set 

 in. They are expressions of this condition and serve to 

 confirm and transmit this tendency. The fact is tremen- 

 dously evident that even the most innocent of symbiotic, de- 

 pendent or attached conditions of growth is the leaven of 

 progressive degeneracy. 



It is well known that the critical methods of morphology 

 and embryology have been requisite to determine the origi- 

 nal ancestral independence of the most debased of para- 

 sites. While the doctors of the Middle Ages wondered over 

 the barnacles and pictured them as growing on trees, drop- 

 ping thence to the ground transformed into geese, their 

 real nature as debased crustaceans was not unfolded till 

 the life history of the creatures showed that their early 

 stages were free and predatory, and the adult condition 

 one of extreme adaptation by progressive loss of functions 

 and organs. Thus the parasitic and dependent habit is, in 

 metazoan life, preceded by a free and predatory condition. 



