474 THE HUMAN BODY. 



shelters the fats. Liebig, indeed, in a very celebrated dis- 

 cussion, maintained that fats were formed from carbohydrates 

 He showed that a cow gave out more butter in its milk than 

 it received fats in its food; and Huber, the blind naturalist, 

 showed that bees still made wax (a fatty body) for a time 

 when fed on pure sugar; and indefinitely when fed on honey. 

 Consequently, for a long time, an origin of fats from carbo- 

 hydrates was supposed to be proved; but their possible origin 

 from proteids (a possibility now shown to be a certainty) was 

 neglected, and the validity of the above proofs of their carbo- 

 hydrate origin is thus upset. The cow may have made its 

 butter from proteids; the bees, fed on sugar, their wax for a 

 time from proteids already in their bodies; and, indefinitely, 

 when fed on honey, from the proteids in that substance. 

 Moreover, animals (ducks) fed on abundant rice, which con- 

 tains much carbohydrate but very little proteid or fat, remain 

 lean; while if some fat be added they lay up fat. 



Persons who fatten cattle for the butcher find that the 

 foods useful for the purpose all contain proteids, carbohy- 

 drates, and fats, and that rapid fattening is only obtained 

 with foods containing a good deal of fat; as oilcake, milk, 

 or Indian corn. Taking all the facts into account we shall 

 probably not be wrong in concluding that nearly all the 

 bodily fat is manufactured either from fats or proteids; 

 from fats easier than from anything else, but when much 

 proteid is eaten some is made from it also. Carbohydrates 

 alone do not fatten; the animal body cannot make its pal- 

 matin, etc., out of them. Nevertheless they are, indirectly, 

 important fattening foods when given with others, since, 

 being oxidized instead of it, they protect the fat formed. 



Dietetics. That "one man's meat may be another man's 

 poison" is a familiar saying, and one that, no doubt, ex 

 presses a certain amount of truth; but the difference probably 

 depends on the varying digestive powers of individuals 

 rather than on peculiarities in their laws of cell nutrition : 

 we all need about the same amount of proteids, fats, and 

 carbohydrates for each kilogram of body weight; but all of 

 us cannot digest the same varieties of them equally well : it 

 is also a matter of common experience that some foods have 

 peculiar, almost poisonous, effects on certain persons. Some 

 people are made ill by mutton, which the majority digest 

 better than beef. 



