NECESSITY OF A VAEIED DIET. 129 



which is our best guide as regards the quantity and the 

 selection of food, indicates that a varied diet is necessary to 

 proper nutrition. This fact is also exemplified in a marked 

 degree in long voyages and in the alimentation of armies, 

 when, from necessity or otherwise, the necessary variety of 

 aliment is not presented. Analytical chemistry fails to show 

 why this change in alimentary principles is necessary, or in 

 what the deficiency in a single kind of diet consists ; but it 

 is nevertheless true that after the organic constituents of 

 the organism have appropriated the nutritious elements of 

 particular kinds of food for a certain time, they lose the 

 power of inducing the catalytic changes necessary to proper 

 nutrition, and a supply of other material is imperatively de- 

 manded. This fact is particularly well marked when the 

 diet consists in great part of salted meats, though it is also 

 the case when any single variety of fresh meat is constantly 

 used. After long confinement to a diet restricted as regards 

 variety, a supply of other material, such as fresh vegetables, 

 the organic acids, and articles which are called generally 

 anti-scorbutics, becomes indispensable ; otherwise the modifi- 

 cations in nutrition and in the constitution of the blood in- 

 cident to the scorbutic condition are sure to be developed. 



It is thus apparent that an adequate quantity and proper 

 quality of food is not all that is demanded in alimentation ; 

 and those who have the responsibility of regulating the diet 

 of a large number of persons must bear in mind the fact that 

 the organism demands considerable variety. Fresh vegeta- 

 bles, fruits, etc., should be taken at the proper seasons. It is 

 almost always found, when there is of necessity some same- 

 ness of diet, that there is a general craving for particular ar- 

 ticles, and these, if possible, should be supplied. This was 

 frequently exemplified in the late war. At times when the 

 diet was necessarily somewhat monotonous, there was an al- 

 most universal craving for onions and raw potatoes, which 

 were found by the surgeons to be excellent anti-scorbutics. 



In those who supply their own food the question of vari- 



