A Fantasy on Ageing 191 



for growth. In the early stages the ealorie intake may l^e 

 reasonable and although the ehikl does not grow the liver 

 cells fill with fat and the liver itself becomes enormous. 

 Judging by what happens in protozoa one would expect that 

 the expectation of life of each of these liver cells would be 

 curtailed and also its powers of regeneration. The cells 

 certainly disappear before their time and are replaced with 

 fibrous tissue. If the child survives kwashiorkor in his early 

 days he often has a small cirrhotic liver in later life. Alcohol 

 again may not be the tOcxin which kills the liver cell of the 

 heavy drinker so much as the food which overnourishes it. 

 It is highly suggestive in this connection and reminiscent of 

 Tokophrya that the nucleic acids should accelerate the process 

 of regeneration in liver cells (Newman and Grossman, 1951). 

 The pancreatic islets of the obese may not die from over- 

 work but from overnutrition. Why overnutrition should 

 hasten the death of a cell has not yet been established but it 

 is reasonable to consider it with the apparently opposite 

 problem of why undernutrition should prolong its life. 

 Starvation has been found to raise the nuclear/cytoplasmic 

 ratio of the liver cell of the adult rat. Marion Harrison (1953), 

 one of our collaborators, found that starvation reduced the 

 cytoplasm of the liver cell and to some extent the ribonucleic 

 acid within it, but not the deoxy nucleic acid of the nucleus itself 

 (see also Davidson and Waymouth, 1944). The cells in an 

 organ which is undergoing active growth and hypertrophy 

 are also small and have a large nuclear/cytoplasmic ratio. 

 Overnutrition increases the reserve materials within all 

 animals whether unicellular or multicellular and, although the 

 segregation of the storage materials within specialized cells 

 in the higher organisms may "protect" other also specialized 

 cells from the full impact of overnutrition, all the cells in the 

 body must be subjected to it to some extent. Why should this 

 be so lethal? At one time we were struck by the fact that in 

 Tokophrya, as in man, this decreased the ratio of the nucleus 

 to the mass of the cell and that, for some reason connected 

 with this, the more vulnerable cells then succumb. The 



