240 THE PRINCIPLES OF HEREDITY 



the instinct it is wonderfully exact. Normally adults trust 

 exclusively to it. Guided by the instinct they eat and drink 

 of the things they enjoy to the extent of their desires. Man 

 is an omnivorous animal. No one food contains all the 

 constituents necessary to him in exactly the right propor- 

 tions, though many foods contain all the constituents in 

 wrong proportions. If, then, he is restricted to one article of 

 diet, he eats largely and wastefully ; he must devour too 

 much of some constituents that are in excess to get suffici- 

 ency of those that are in deficiency. Hence the huge meals 

 of meat made by the carnivorous Esquimaux, or of rice made 

 by the vegetarian Hindoos. When a varied diet is adopted 

 the meals are smaller, because instinct so directs the choice 

 that the different constituents are combined in the right 

 proportion. Except when our instincts are perverted by 

 disease or acquired characters, we delight in dishes that have 

 in excess the constituents in which we are deficient, and we 

 tire of those which have in excess constituents that have 

 become superfluous to us. 1 



399. The instincts of curiosity and imitativeness are of the 

 highest importance. In every species of animal they are 

 developed in direct proportion to the power of making mental 

 acquirements. They are the principal vehicles by means of 



1 I have had the temerity to put this theory into practice. With one 

 exception, almost from babyhood my child has been allowed to eat 

 exactly what he wished and to any extent that he wished. He was not 

 made to eat anything he did not like. The exception was vinegar, for 

 which he had a fad, and as to which he was checked. He has shown no 

 inclination to excess in any other particular. His desire proved to be 

 chiefly for farinaceous foods. His appetite, as was expected, is small, but 

 from the first he has been very active and free from ailments. It is 

 probable that so-called greedy children are merely starved children 

 starved of some necessary constituent of diet, which in England is 

 usually sugar. Such children, like famished men, generally eat to 

 excess. Greediness is less common among adults, who have the power of 

 choosing and combining their own diets. No doubt the appetites of 

 children like those of adults vary with the individual. But, propor- 

 tionately to the sizes of children, their appetites are often larger than 

 those of older people. This is usually attributed to the demands of 

 growth. But a minute quantity of food should be sufficient to supply 

 the microscopic amount of daily growth made by a child. Though 

 growth is very rapid during intra-uterine life, pregnant women have not 

 noticeably larger appetites than non-pregnant women. The larger 

 appetites of children, therefore, are probably due to the fact that they are 

 seldom allowed to select their own diet. Modern men are larger and 

 presumably stronger and more robust than their ancestors of four or five 

 hundred years ago. Presumably the increase of size is due to more and 

 better food, especially to that very concentrated and nourishing food, 

 sugar. 



