GENERAL METABOLISM. 649 



more protein than a bony person with but slight muscular development. 

 On the other hand, we are at present unable to measure the actual amount 

 of work done by people of different callings, which would give us exact 

 data for the calorific requirements. At all events, the protein content of 

 the food is practically of chief importance, as regards a definite food 

 requirement. From a practical standpoint, furthermore, it is hardly 

 desirable to have a definite minimum established as regards the amount 

 of protein required by the organism. If it should be attempted to 

 make the food contain such an amount, it would be very easy to fall 

 below it from time to time, and this would lead to albumin losses from 

 the body. There is absolutely no reason, aside from the expense, of 

 being afraid that too much albumin will be eaten. The body easily 

 assumes a state of equilibrium with a larger supply of protein. We have 

 seen that it is very difficult indeed to cause an accumulation of albumin 

 in the body. 



The question of expense is the most important factor as regards the best 

 way to meet the calorific requirements with non-nitrogenous food after 

 the organism has received sufficient albumin. Carbohydrates are cheapest. 

 The amount of these in the above-mentioned diets is also considerable. 

 They can be easily taken care of by the intestine. Fat, unfortunately, is 

 very expensive, although, to be sure, an equal weight of it has more than 

 twice as much calorific value as the carbohydrates. 



In this connection we must call attention to a peculiarity. When persons 

 are obliged to resort to a definite diet which is about the same from day to 

 day, they often lose in weight, and show even in their outward appearance 

 that they are not well-nourished, even although there may have been enough 

 calories in the food. We can to some extent understand that a diet which 

 is absolutely non-irritating, and remains exactly the same from day to day, 

 will not be as nutritious as one of different composition which may not 

 have any greater calorific value. We have seen that the smell, taste, and 

 other sensations play an important part in the preparation of the digestive 

 fluids. Now when tne sensation is exactly the same from day to day, 

 and the food is free from irritating substances, it soon fails to cause 

 any stimulation of these sensations. The way in which the food is pre- 

 pared also exerts an important effect. This governs largely the extent to 

 which the smell and taste nerves are stimulated, and moreover provides 

 for a greater utilization of the food material. 



One question which has been considerably discussed is whether the 

 human organism should obtain its food preferably from the vegetable 

 kingdom exclusively, or whether a mixed diet is preferable. 1 Certain 



1 Cf. G. von Bunge: Der Vegetarianismus, 2d edition. A. Hirschwald Berlin, 1901. 

 Ferdinand Hueppe: Der moderne Vegetarianismus. A. Hirschwald, Berlin, 1900. W. 

 Caspari: Physiologische Studien iiber Vegetarianismus. Martin Hager, Bonn, 1905. 



