32 president's address. 



happens through a succession of functions being discharged by 

 one and the same organ. Each function is a resultant of several 

 components, of which one constitutes the chief or primary func- 

 tion, while the others are lower or secondary functions. Dimi- 

 nution of the importance of the chief function, with increase of 

 the importance of a secondary function, alters the entire result- 

 ant function, the secondary gradually rises to the chief function, 

 the resultant function becomes different, and the consequence of 

 the whole process is the transformation of the organ." This 

 principle is considered to be a complete answer to the difficulty 

 so strongly insisted on by Mivart, the incompetency of natural 

 selection to account for the incipient stages of subsequently use- 

 ful structures. Dohrn's statement of his pnnciple would seem 

 not to be very different fi'om Darwin's, though a little more 

 definitely stated. Darwin says, ''The same organ having per- 

 formed simultaneously very different functions, and then having 

 been in part or in whole specialised for one function, and two 

 distinct organs having performed at the same time the same 

 function, the one ha^'ing been perfected whilst aided by the 

 other, must often have largely facilitated transition." 



At a meeting of the Cambridge Philosophical Society, held on 

 October 30th, 1876, an account was given by Mr. Bettany of 

 some of the conclusions arrived at by Professor AV. K. Parker 

 and himself on the moi-phology of the skull. The detailed com- 

 parison, for the first time, of the whole of the developmental 

 liistories of skulls which had been liitlierto investigated, includ- 

 ing some very recent researches, had led to some important mo- 

 difications of view. The questions dealt with referred to the 

 cranial elements which appear the earliest. It was sought to 

 discover what parts are axial and wliat parts appendicular. 

 WTicther, indeed, the axis of the body ceases at the middle of 

 the base of the skull, and the latter has to annex properly ap- 

 pendicular stnictures in order to become complete. There was 

 mucli difficulty in determining these points, because in many of 

 the higlier forms tlie earlier stages of development were passed 

 through with great rapidity, and because in otlier cases the adap- 

 tation of the adult form to its special conditions of life more or 



