FOURTH REPORT OF THE DIRECTOR I907 I49 



social and apparently harmless or even mutually advantageous to 

 the participants, it is probable that the outcome is infallibly del- 

 eterious. 



The glass rope sponge (Hyalonema) has its coil of rope, by which 

 it anchors itself to the sea bottom, incrusted and shielded by a coral 

 (Polythoa) , which spreads like a thin wrap of felt all about it, while its 

 ally the Venus Flowerbasket (Euplectella) imprisons a crab in its in- 

 terior behind the bars it throws across its aperture but feeds it with 

 ever changing water currents; worms and anthozoan corals grow to 

 gether, with the tubes of the former surrounded b}^ the cells of the 

 latter, both sweeping the water currents together 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 harmless or 

 positively advantageous to all parties involved; that is advan- 

 tageous in the sense that they make life easier, less arduous, dis- 

 courage activity and perfect adaptation. Perfect adaptation, 

 however advantageous to the individual concerned, is the very 

 expression of degeneration in symbiotic life. Throughout nature 

 complete adaptation makes for stability and long life, incomplete 

 adaptation for the restless activity which leads to progress. 



The general effect then 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 tremendously evident that even the 

 most innocent of symbiotic, dependent 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 original ancestral 

 independence of the most debased of parasites. While the doctors 

 of the middle ages wondered over the barnacles and pictured them 

 as growing on trees, dropping thence to the ground transformed 

 into geese, their real nature as debased crustaceans was not un- 

 folded 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 always preceded by a 



