54 ORGANIC DEPENDENCE AND DISEASE 



of this Coblentzian species but have seen no other shell 

 used for attachment nor have I found record of any other. 

 Though it is not practicable to use percentages with 

 reference to the frequency of this occurrence, the palpable 

 fact remains that, as between these two closely allied if 

 not identical corals, growing in different and remote basins 

 of the sea, one selects a gastropod, the other selects a 

 brachiopod as its base of attachment. Emphasis is put 

 on the word "selects," for among the brilliant examples 

 of selective adaptation none could be more striking than 

 this. The floor of the New York Devonian sea was covered 

 with Chonetes and of the Rhenish sea with gastropods, dur- 

 ing the life of this coral. Were either wanting in the 

 other fauna, hundreds of other species of organisms lined 

 the sea bottom. It is very impressive to find the evidence 

 of this singular Devonian association of coral and worm 

 from parts of the world as remote from each other as 

 New York, northern Brazil, western Europe and Con- 

 stantinople. The fact that in chronology the New York 

 occurrence is later than the rest (Lower Devonian) seems 

 to indicate a quick spread of this adjustment over the sandy 

 sea bottom of the early Devonian of the world,^ from which 

 the deeper contemporary waters of New York were ex- 

 cepted and in which region this symbiosis did not arrive 

 till the next succeeding stage. Of its ultimate fate a nega- 

 tive evidence permits us only to say that it went out with 

 the Hamilton stage and did not return with the partial re- 

 turn of that fauna in central New York during the time 

 that is reckoned as of the next succeeding stage — the 

 Ithaca-Portage time of the Upper Devonian. 



I have not attempted to escape the obvious interpreta- 

 tion of these phenomena nor to avoid its expression in 

 terms of psychic function. To biologists who still find the 

 term "instinct" a comfortable receptacle for such reac- 



1 Save in the early Devonian of austral latitudes where the fauna is very 

 unlike that of the rest of the world. 



