MILK FAT FROM CARBOHYDRATES 425 



the healthy adult individual that he should really have some- 

 thing to eat (a postulate which unfortunately in this best of 

 all worlds is apparently very incompletely satisfied) than 

 that the food, provided in a general way it is palatable, 

 should have any particular fixed composition. How often 

 has the author been amazed at the patience shown by his col- 

 leagues in active medical practice toward the very silly 

 questions about diet with which old ladies of both sexes are 

 in the habit of plying them in their anxiety for their relatives 

 or from pure love of asking questions. But it is a very dif- 

 ferent matter when we are dealing with the feeding of in- 

 fants. Here there is room for the most painstaking care 

 and attention from a practical standpoint. And it is par- 

 ticularly important that the physician keep constantly before 

 him the fact that the infant's supply of fat is directly depen- 

 dent upon the food which is ingested by the nurse and upon 

 the character of her fat deposits. This is no "nursery 

 tale"; it is a scientifically proved fact. Thus, often the 

 trouble met in changing wet nurses may in the last count 

 be connected with the biochemistry of fat ; and there is jus- 

 tice in the demand that in the first place the milk of nursing 

 women be kept constant by selection of an appropriate fat- 

 mixture, and again that by proper feeding of cows a milk be 

 produced with fat similar to the fat of human milk. 74 In 

 spite of the enormous extent of milk literature, the details 

 of which cannot possibly be entered into here, a great deal 

 of work remains to be done before we can clearly appreciate 

 how far race, heredity, mode of nutrition, sexual activity, 

 season, calory-requirements of the growing body, etc., affect 

 the composition of milk. 75 



Origin of Milk Fat from the Carbohydrates of Food. 

 A portion of the fat in milk doubtless comes from the carbo- 

 hydrates of food. Thus an experiment upon a cow fed for 

 three months on material poor in fat (hay and grain-food 



T4 Engel and Plaut, Wiener klin. Wochenschr., 1906, No. 898. 

 75 Cf. G. von Wendt, Skandin. Arch, f . Physiol., 21, 89, 1909. 



