A MECHANISM FOR ORGANIC CORRELATION 1 



G. 3. PARKER 

 Professor of Zoology, Harvard University 



The year 1909 is notable for its many historical asso- 

 ciations. It is not only the fiftieth anniversary of the 

 publication of ' ' The Origin of Species, ' ' but it is also the 

 centenary of the birth of Charles Darwin and of the 

 publication of Lamarck 's 4 ' Philosophie Zoologique. ' ' To 

 the American its associations with Lincoln are precious 

 memories. But it is not to these historical matters that 

 I wish to refer. Science ever looks forward, not back- 

 ward, and it is on certain modern aspects of the move- 

 ments centering about the problem of evolution and espe- 

 cially on those connected with the name of Darwin that 

 I wish to speak. 



Although biologists have been familiar with Darwin's 

 theory of natural selection for almost fifty years, it must 

 be confessed that they are only at the threshold of the 

 problem of evolution. That species have arisen by trans- 

 mutation is now universally admitted, but how transmuta- 

 tion has been accomplished remains at present one of the 

 unsolved riddles. The Lamarckian factors, though pos- 

 sible, must be set down as still unproved. Natural selec- 

 tion, so far as observation and experiment go, seems to 

 play a real part in transmutation, but the extent of its 

 application is still a matter of much uncertainty. Even 

 the recently advanced mutation theory, on which hopes 

 at one time ran high, is coming to assume at best a supple- 

 mentary role. In fact it is evident that the most serious 

 efforts of the past have failed of full accomplishment and 

 it seems likely that the process of transformation is not 

 exclusively dependent upon any single principle, but is 

 of great complexity involving in all probability a consid- 



1 Bead before the Boston Society of Natural History, February 12, 1909. 

 212 



