igoi] Charron — Fat in the Animal Body. 133 



Protein is a class of substance characterised by the presence 

 in its composition of nitrogen to the amount of about 16 per cent. 

 Like the carbohydrates and the fats it contains carbon, hydrogen 

 and oxygen, but it stands apart from these two on account of its 

 nitrogen content. Carbohydrates consist of those substances like 

 sugars, starch and fibre, which are composed of carbon, hydrogen 

 and oxygen united in such a way that the relation of the latter to 

 the former is in the ratio of one atom of the latter to two atoms 

 of the former, as in water. 



Fat is a substance composed of exactly the same elements as 

 the carbohydrates, but whose atoms are arranged differently in 

 the molecule. The atoms of hydrogen to those of oxygen are not 

 in the same proportion. It contains no nitrogen and is thus quite 

 distinct from protein. 



Now do you believe that fat as it is found in the animal body is a 

 simple compound of always exactly the same definite composition ? 

 If so, a'low me to inform you that you are mistaken. Fat 

 is not a simple compound, but a mixture of three, some- 

 times more compounds of analogous nature. The three 

 principal compounds are stearin, palmitin and olein. The first 

 two are solid at ordinary temperature and the latter is a liquid. 

 The amount of olein is always more or less in excess of the other 

 two, and it with the help of the heat of the living body keeps them 

 in the liquid form. Olein really acts as a solvent towards stearin 

 and palmitin You must have noticed that in the living body fat 

 exists in the liquid state. As soon as death occurs there is a 

 gradual falling off in the te-nperature of the body, rigor mortis 

 sets in, and the fat becomes solidified. The mixture of those three 

 substances is more or less firm according to the smaller or greater 

 amount of olein it contains. 



I told you that fat is one of the component parts of food. 

 You are perhaps anxious to know what part it plays in the 

 nutrition of the body, and what transformations it undergoes 

 previous to becoming an integral part of the same. 



Fat is one of the best producers of heat, in fact, it is the m.ost 

 powerful heat producer ot all the food stuffs. A glance at its 

 composition will convince you as to the truth of this assertion. 

 The composition of one of the fats (olein) is expressed by the 



