188 



R. A. McCance and E. M. Widdowson 



accentuate the overnutrition and the cells may become very 

 large; nuclear growth and division then cease and the ceJls die. 

 The higher organisms differ from the protozoa in that they 

 all have some innate mechanism of control which adjusts 

 their food intake to their requirements. In them, as in 

 Tokophrya but not in most protozoa, growth is limited and 



1 



360- 

 320- 

 280 

 240- 



200- 



oj l6o^ 



I20- 



80- 



40 



O 



/ 



Well nourished 



/ 



/ 



/ 



/ 



/ 



/ 



.<r. 



Undernourished 



-1 1 1 1 1 1 1 — 



O 4 8 12 16 20 24 28 



S weeks old. weeks of experiment 



Fiu. 1. Growth of two pigs, one well nourished, the other 

 undernourislied. 



life is limited, but both can be modified by nutrition. Fig. 1 

 shows the growth curve of two pigs, littermates; one had been 

 fed on unlimited amounts of a first-class diet for growth 

 purposes and the other had had exactly the same diet, very 

 severely curtailed. It is known from the work on rats (McCay, 

 Maynard, Sperling and Barnes, 1939; Brody, 1945; McCay, 

 1952) that this small pig might have been kept like this 

 possibly even for years, while its littermate lived out its 

 normal life and died. Whether it would then have grown and 

 matured normally as the rat does remains to be discovered. 



