208 General Discussion 



seven years ago, and it is still in progress. Of course we lived with the 

 illusion that we can avoid disease. This illusion covers all studies in 

 gerontology, and will remain an illusion, because we shall never be able 

 to study pure ageing without the influence of exogenous factors. 



To go back to Dr. Lansing's contribution about changes in the 

 constitution of tlie tissue according to age, we are trying to analyse the 

 whole animal. We feed groups of animals of different ages on a standard 

 diet, and tlien we dry-powder the whole animal. The first result of 

 these analyses is that the main effect of ageing is the putting on of fat 

 and lipid substances. But this is already known. One of my previous 

 masters, Terroine in Strasbourg, demonstrated thirty years ago that 

 when you analyse tissues of animals, if you are to have comparative 

 figures you must starve your animals to death before you analyse. When 

 you do that, and you take kidneys or liver or muscle of different animals 

 of the same species, the results are comparable. So we are going to do 

 that. But as regards comparing results or exchanging of possibilities, we 

 could just as well exchange powdered animals. I shall do what I can to 

 analyse the powdered animals from many points of view, I shall do 

 gross analyses and some of the amino acids etc., but many other 

 laboratories may do what I am unable to do. So if we are thinking of 

 working along those lines, we might help each other. I have not pub- 

 lished anything yet about these mice, perhaps I never shall, but I am 

 ready to compare and to exchange powdered mice of that inbred 

 colony with anyone who wants help in that way. 



