1909 J Rittef: Halocynthia johnsoni n. sp. 89 



scientific function other than to interpret nature itself. This 

 becomes obvious the moment one reflects that the experimenter 

 has always to go, finally, to nature unexperimented upon by 

 man for the material with which to experiment. 



Cabrillo's ships entered the bay now known as San Diego 

 in 1542. Is there any likelihood based on observation that had 

 thai navigator collected some of these ascidians and could we 

 today compare them with the specimens taken this summer, the 

 two lots would present any recognizable difference ? And does 

 any doubt that the description here given of the species, pro- 

 vided it be accurate, will apply without modification to specimens 

 that may be collected say five hundred years from now? But 

 one bent first and foremost on inquiring how the animals came 

 to be adapted to their conditions might say that if they have 

 not changed since Cabrillo visited the Locality and do not change 

 in the next five hundred years, this means that the conditions 

 have not changed and will not in the time specified. This ex- 

 pression of view would be made probably with the implication 

 that change in environment and environed organism are wholly 

 and inseparably linked together, and that at least so far adap- 

 tation can be accounted for. Let us accept this view provision- 

 ally. We can say then that sometime in the past (how many 

 years before Oabrillo came, we have not the remotest idea) an 

 ascidian species existed here or in some locality not remote that 

 was not the same as II. johnsoni. In course of ages a gradual 

 geological or other physical or biological change in the Local 

 conditions occurred and pari passu, the ascidian underwent 

 change and E. johnsoni was produced. Or, on the supposition 

 that the ancestral form lived in some other locality slightly dif- 

 ferent from the San Diego bay region, we would' presume that 

 the new and different environment which caused the new adap- 

 tation was reached by gradual migration. 



But even if this line of reasoning as to how the adaptation 

 came about be accepted at its full face value, we are bound to 

 admit that it is not very satisfactory, especially when the at- 

 tempt is made to apply it in a specific instance like this. What 

 exactly was the nature of the geological or other change in the 

 locality? Change of level within comparatively recent geolo-- 



