GENERAL DISCUSSION 



Amoroso : We now come to the group discussion on the significance 

 and limitations of the work discussed earlier from the aspect of 

 ageing processes in general. In this discussion we might endeavour 

 to establish broad areas of agreement, both in fact and interpretation 

 as well as indicating those points of difference whose resolution might 

 be expected to advance our knowledge of the problem of ageing. 



A suggestion emanating from Professor Huggett at an earlier stage 

 seems to me to provide a useful point of departure. Might I ask 

 him to open the discussion? 



Huggett: I wondered whether we could perhaps start at the be- 

 ginning with simple definitions and see whether we can agree on 

 those and then afterwards we could amplify into more general 

 interchange. 



Amoroso: I should have thought that in the course of our de- 

 liberations we have used the word ageing in every one of its possible 

 connotations, so that I am a little doubtful whether we can define 

 it more precisely than Dr. Parkes when he says it is the changing 

 chronological events in the life history of the individual. 



Corner: Is it not necessary to put the word 'irreversible' into 

 Parkes' definition? If my arms are extended one moment and 

 retracted the next, that is a change with time but it is not ageing. 

 I am suggesting that in your definition that ageing is a change of 

 organisms with time, you must say 'irreversible' changes. 



Parkes : Well, in your example, you are using up ultimate capacity 

 for extension. You are living on your vital capital. 



Dempsey : We are going to get into difficulty, in the field of repro- 

 duction, with the definition of ageing as progressive changes with 

 time, because somewhere along the line one of the reproductive cells 

 has got to be rejuvenated, hasn't it, and that is still a progressive 

 time change. 



Parkes : Yes, you have got to use a longer time scale. 



Dempsey : But somewhere the clock has got to be wound up again. 

 The germ cells might be ageing as they grow older in an individual 

 and then comes fertilization and what happens? Does the clock 

 suddenly get wound up again and start all over again at fertiliza- 

 tion? Fertilization is still a progressive change with time. 



Wislocki: The term ageing, in the broadest sense in which it is 

 used, has the connotation of any progressive change, including 

 growth, differentiation, maturation and senescence. For many pur- 

 poses, however, the term ageing is better defined as senescence, by 



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