44 IMPORTANCE OF A MIXED DIET. [CHAP. I. 



It is necessary to the support of nutrition,, that these proxi- 

 mate principles should be supplied in proper quantity to the blood, 

 from time to time, together with a due proportion of water ; and 

 as the human body is composed of a variety of textures, differ- 

 ing in their chemical composition so a variety of food is required 

 for its perfect nourishment. This statement, which appears most 

 reasonable prior to experience, is fully borne out by the results 

 of the various experiments on the nutritive power of different sub- 

 stances, from the time of Papin to the present day. No one 

 proximate principle is of itself adequate to support life : if any 

 such substance be administered alone to animals, they will perish 

 sooner or later, with signs of waste and destruction in various 

 textures. This had been long ago ascertained respecting gelatine ; 

 but a commission appointed by the French Academy have lately 

 reported that it applies equally to albumen, caseine, or fibrine, 

 if employed alone ; and that neither animals nor man should be 

 restricted to any course of diet, which does not contain all the 

 proximate elements of their frame. 



These facts should be made known to, and impressed upon all, 

 whose position in society leads them to superintend the adminis- 

 tration of food to a number of human beings congregated in prisons, 

 workhouses, or other public institutions. A complex machine, 

 made up of many different kinds of substances, requires for its 

 repair a corresponding variety of materials. The fabric of man's 

 body is a piece of mechanism compounded of divers parts, de- 

 rived from albumen, fibrine, gelatine, &c. ; and the material, which 

 is to supply the wear and tear that continually go on in it, ought 

 to contain these substances. It is even more important for suffi- 

 cient nourishment that attention should be paid to the quality than 

 to the quantity of the food administered. 



By the function of digestion, a fluid (the chyle] is prepared, 

 which contains those constituents of the food that are adapted to 

 nourish the body, and the first step of the nutrient process consists 

 in the addition of this new supply of nutritious material to the 

 blood. A further stage of this process is that whereby the several 

 proximate principles are separated in order to be applied to the 

 support of their appropriate textures ; as albumen, to the albuminous 

 tissues ; fibrine, to the fibrinous. These two principles have already 

 appeared in the chyle, and pass with it into the blood-vessels, in 

 which all the changes necessary to nutrition take place. It is pro- 

 bable that gelatine is formed in the blood, but is attracted from it 

 by its proper tissues immediately upon its formation, so that it 



