PREFACE 



This book is a compilation. It was written as an aid to my own 

 research, in a subject where it is difficult to know where to 

 begin, but I hope that the references, at least, will be useful to 

 others. 



The denunciation of a subject and its current theoretical 

 basis as 'unsatisfactory' is a relatively easy exercise — dealing 

 with it satisfactorily is quite another matter. No biological 

 treatment of senescence can hope to be satisfactory in the 

 absence of a great deal of factual information which at present 

 is not there. I have attempted to collect as much of this informa- 

 tion as possible: since most of it comes from fields in which I 

 have no experience, there are bound to be errors both of fact 

 and of deduction in such a survey, and I hope that they will 

 be pointed out to me. 



I am deeply grateful to Professor Peter Medawar, F.R.S., 

 under whom I have worked, to Professor J. B. S. Haldane, 

 F.R.S., for kindly drawing my attention to a number of refer- 

 ences I would not otherwise have seen, and to many colleagues 

 whom I have molested for information or criticism, and whose 

 help and advice has been invaluable, though they bear no 

 responsibility for the result. I am also profoundly indebted to 

 the Nuffield Foundation for several years' financial support, to 

 Dr. Harrison Matthews, Director of the London Zoo, for access 

 to its records, and to Miss Rosemary Birbeck for much help in 

 preparing the manuscript and bibliography. 



ALEX COMFORT 



December 1954 



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