viii Contents 



PAGE 



The use of inbred strains of animals in experimental 

 gerontology 



by O. Muhlbock ....... 115 



Discussion : Best, Bourliere, Bourne, Danielli, Franklin, 

 Friedman, Gillman, Krohn, Landowne, Muhlbock, 

 Olbrich, Parkes, Tunbridge, Verzar . . . .125 



Twin data on the genetics of ageing 



by F. J. Kallmann ....... 131 



Discussion: Best, Bourne, Danielli, Friedman, Gillman, 



Kallmann, Lewis, Lorge, Nicolaysen, Olbrich . . 143 



Methodological problems in the study of changes in 

 human performance with age 



by A. T. Welford 149 



Methodology of the study of intelligence and emotion in 

 ageing 



by I. Lorge ........ 170 



Discussion: Best, Danielli, Friedman, Lewis, Lorge, 

 Olbrich, Parkes, Tunbridge, Verzar-McDougall, 

 Welford 182 



General Discussion: Best, Bourne, Friedman, Gillman, 



Lorge, Nicolaysen, Olbrich, Verzar, Zilli . . .188 



Chairman's closing remarks 



C. H. Best 195 



