384 NUTRITION. 



nized " that the nutriment which produces the most rapid 

 and pronounced fattening is precisely that which joins to the 

 proper proportion of albuminoid substances the greatest pro- 

 portion of fatty principles." 



Animals cannot be fattened without a certain variety in 

 the regimen. We have already discussed the necessity of a 

 varied diet, and have shown that an animal will die of star- 

 vation when confined exclusively to one class of principles, 

 even if this be of the most nutritious character ; a and it is 

 not necessary to refer again to the experiments which have 

 demonstrated that a diet confined exclusively to starch, 

 sugar, or fat, or even pure albumen or fibrin, cannot sus- 

 tain life, much less fatten an animal. We are prepared, 

 then, to understand why, in the pigs experimented upon by 

 Boussingault, a regimen confined to potatoes did not prove 

 to be fattening, notwithstanding the large proportion of 

 starch, 3 and that fat was produced in abundance only when 

 the food presented the proper variety of principles. 



Yery little is known concerning the precise mechanism 

 of the production of fat. The experiments of Boussingault 

 seem to leave no doubt that it may be formed from any kind 

 of food, even when it is exclusively nitrogenized ; 4 but it is, 

 nevertheless, a matter of common observation that certain 

 articles of diet are more favorable to its deposition than 

 others ; and it is also true that the herbivora are fattened 

 much more readily, as a rule, than the carnivora. 



Theoretical considerations would immediately point to 

 starch and sugar as the elements of food most easily con- 

 vertible into fat, as they contain the same elements, though 

 in different proportions ; and it is more than probable that 



1 BOUSSINGAULT, op. cit., p. 16Y. 



2 See vol. ii., Alimentation, p. 128. 



3 Op. cit., p. 122. 



4 The researches of Wurtz have shown that certain of the albuminoid prin- 

 ciples can be converted into fatty acids by the action of an alkali and heat, and 

 that this may also occur spontaneously (WURTZ, Sur la transformation de la 

 fibrine en acide butyrlque. Comptes rendus, Paris, 1844, tome xviii., p. 704). 



