No. 508] MECHANISM FOR ORGANIC CORRELATION 



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erable number of factors. Of these factors we are only 

 beginning to get glimpses. I believe they will come into 

 clearer view only as we progress in the solution of general 

 biological problems. It is my intention to bring before 

 you very briefly one of these lines of progress and to 

 point out its possible bearing on the problem of evolution. 



You are all doubtless familiar with the claim that 

 Darwinism or natural selection is at best only a partial 

 or insufficient factor in evolution. Its actual workings 

 seem to be concerned with the elimination of only the 

 most poorly adapted members of any stock ; it is a process 

 that is not closely enough adjusted to call forth those 

 slight but constant differences which every systematist 

 recognizes as the distinguishing marks of a species. To 

 quote from a recent criticism : 



Every student of systematic zoology or botany has a keen realization 

 ... of the fact that a majority of the distinguishing characters which 

 he recognizes in the various species . . . that come under his eye are 

 of a sort that reveal to him no trace of particular utility. 



For this reason it is believed that these characters could 

 not have been produced through natural selection. I 

 hope to show you, however, that we can make the admis- 

 sion implied in this quotation, to the effect that specific 

 characters are not necessarily useful, and still be able 

 to explain their occurrence and fixity through Darwinism. 



A general outline of this proposition has already been 

 given by Plate in his consideration of correlation. Ac- 

 cording to this author the development of a specific char- 

 acter of no special use may take place through correla- 

 tion, that is, through that unknown law of growth by 

 which an indifferent organ may be so bound up with or 

 related to a useful organ that it, the indifferent organ, is 

 perfected along with the useful organ as this latter is 

 developed or specialized through selection. In this way 

 it is conceivable that a specific character, even though 

 useless, may arise at least indirectly through natural 

 selection. It is to be noted that Plate's conception of 

 the mechanism of correlation is not detailed; m fact, he 



