NUTRIMENT 441 



special conditions, as when doing hard muscular work in cold 

 climates, we long for the particular constituents, for example, fat 

 and sugar, which are then especially needed. Excess of this or that 

 constituent may cause injury (e.g. gout) in susceptible individuals ; 

 individuals may vary unfavourably so as to desire excess ; and 

 often individuals develop abnormal and injurious tastes, as for 

 alcohol or opium. We shall consider these abnormal desires 

 separately ; but meanwhile it may be stated in general terms that 

 instinct impels the individual to consume about the right quantity 

 of nutriment, and to combine the right constituents in about the 

 right proportions. 



723. Such nutriment as the normal individual receives, pene- 

 trates to all parts of his body and nourishes all his tissues. It 

 is possible to control the quantity taken and so produce the general 

 effects of extreme starvation, or over-feeding, or anything between ; 

 but beyond this, our power is very limited. For example, we 

 cannot by special forms of diet increase the size of the muscles 

 as compared to the glands, or suppress one mental trait (e.g. the 

 sporting instinct) while developing another (e.g. mathematical 

 talent). 1 Apparently when nutriment is in excess no tissue uses 

 an excessive quantity of food, though some structures eliminate 

 the excess, and others store it for the future needs of the whole 

 body. When the supply is defective, some tissues suffer less than 

 others. Thus, inactive structures which need little nutriment, such 

 as bones, or very important structures (e.g. the heart), seem then 

 to develop better than more active or less vitally important parts 

 such as the voluntary muscles. Again, wholly ' inborn ' parts, those 

 for which nutriment supplies not only the material, but the 

 stimulus for growth, appear to suffer less than structures which 

 grow under the stimulus of use. Thus the hair, teeth, eyes, 

 external ears, instincts, memory, and the like, of a half-starved 

 child, seem to develop better than its limbs or its mental acquire- 

 ments, and the structures of a foetus, all or nearly all of which 

 are wholly ' inborn/ appear to have the advantage in their 

 competition for nutriment with the physical acquirements of an 

 ill-nourished mother. 



724. Except in the case of certain unfortunate sections of the 

 community, the British are a well nourished race. Both the 

 quantity and the quality of their nutritive supply are sufficiently 



1 Though this is true of human beings it is not true of all animals. Bees, for 

 example, develop into workers or queens accordingly as they are fed on one kind 

 of food or another, 



