General Discussion 243 



Lansing: But take the male rotifer: it is born, it has no ahmentary 

 traet and dies of starvation within twenty-four hours after fertihzinj^^ 

 Does he die of seneseenee? I'd rather put him in a speeial eateojory, as a 

 very degenerate eharaeter wlio starves to death in tlie twenty-four-hour 

 period that he is busy fertihzing. 



Comfort: But you ean't prove, altliough I think ifs highly improbable, 

 that even the mammal does not die from depletion of something. We 

 know^ so little about the processes which actually operate. I really 

 don't see how we can discriminate. 



Lansing: Well, I rather hope that we can. It seems to me that there 

 are (in spite of my declaration of faith yesterday) in biology a number 

 of bizarre phenomena and organisms which can be pointed out as the 

 exceptions to the rule. When I think of senescence I think of something 

 that happens not to children or to infant rotifers, but to the organism 

 that has become an adult and then undergone some type of change, to 

 wind up dead sooner or later. That's what I mean by senescence. The 

 maturation of the embryo, the new born child, the adolescent, the 

 changes with time prior to maturation to me are not senescence. 



Cowdry: Yours is the downswing of life, then. 



Lansing: Yes, after adulthood has been reached. I can't define 

 adulthood too well, and in some cases the changes that occur in adult- 

 hood are said to be improvements rather than losses. 



Cowdry: You don't have to define it if you just call it the downswing, 

 that implies that after a height you start to go down. 



Comfort: Do you agree then that for various organisms the factors 

 that contribute to that downswing tend to differ very radically from 

 phylum to phylum? 



Lansing: I'm not prepared to agree to that. I think we have special 

 cases which bring about death, but not all death is due to senescence. 



Nicolaysen: If you had the ideal solution, you would know about 

 every cell in the body, what cells are ageing, and then what enzymes are 

 declining, and then you would come to a critical stage where life accord- 

 ing to our orthodox meaning will stop. If we had all that knowledge, we 

 could give a chemical definition of ageing. So we could then work 

 backwards and see how much we know about the vital organs in old age. 

 This might be a useful approach. 



Lansing: The declaration of faith I made yesterday stems in part 

 from the various types of survival curves that Dr. Comfort showed us. 

 The survival curve for Drosophila was virtually identical with the sur- 

 vival curve that one gets for man, except that the time scale is a little 

 off, one is measured in years and the other in days. If one projects the 

 survival curve for rotifers, it's the same sigmoid curve, except that we 

 telescope it a bit further; and we have an identical curve for mice and 

 rats and every other organism that has been measured, which makes me 

 doubt that there are different mechanisms operative. It would be quite 

 a coincidence if all these processes all expressed themselves in the same 

 way. 



Comfort: Raymond Pearl plotted a survival curve for automobiles 

 which was again the same shape! 



