30 THE MENDEL JOURNAL 



evolutionists, recognising the uselessness of diagnostic 

 characters, holds that they have not been evolved by 

 selection, but have arisen spontaneously as muta- 

 tions ; and, with the usual tendency to carry a 

 doctrine to extremes, they maintain that all characters 

 are independent of utility, all arose as mutations. 

 The American investigator. Dr. T. H. Morgan, has 

 published a book specially devoted to this doctrine, 

 in which he endeavours to show that adaptations do 

 not really exist, that mutations have occurred which 

 could only survive under special conditions of life, 

 which in some cases the modified creatures have 

 found, so that habits have been determined by struc- 

 ture, not structure by habits. Thus in the short 

 period of half a century we have had the swing of the 

 pendulum of biological opinion from one extreme to 

 another, from the belief that all characters were 

 adaptive or useful to the belief that none were adap- 

 tive. In the meantime the common-sense view has 

 persisted that some characters were useful and some 

 were not, and that the former were easily modified by 

 conditions of life, the latter unaffected by such con- 

 ditions. It must at any rate be admitted that usually 

 in studying any group of animals we can certainly 

 distinguish between characters which have no visible 

 relation to the maintenance of life and others which 

 are necessary or advantageous to that purpose ; and 

 it is therefore possible to consider the origin of these 

 two kinds of characters separately. 



The human species, in spite of the attention 

 devoted to Anthropology, and although it is to us the 



