424 ORIGIN OF MILK FAT 



no fat is to be seen in the neighborhood of the secretory cells. 

 Arnold concludes from what he saw and with the prevailing 

 status of metabolism in mind, that the component parts of 

 the fat are brought to the lactating cells from without in a 

 water-soluble form, and that the fat is newly constructed 

 from such material within the cellular protoplasm by func- 

 tionating vital processes. 



What then do we really know of the origin of the fat in 

 milk ? In the author 's opinion it is necessary to recognize a 

 three-fold origin. It arises in part from the fats of the food, 

 in part from those of the fat depots of the body, and in part, 

 finally, from the carbohydrates which are undergoing trans- 

 formation in the economy into fat. 



Passage of the Fat of the Food into the Milk. As far 

 as concerns the subject of passage of the fat of the food into 

 the milk, a large number of investigations 72 should be noted, 

 in which studies were made with all sorts of extraneous 

 fats (as cottonseed oil, sun-flower oil, peanut oil, cocoa 

 butter, lindseed oil, oil of sesame, almond oil, palm oil, 

 goose fat, mutton suet, iodized and brominized fats) and 

 which have removed all doubt from the subject. The ques- 

 tion is of interest not only from a general scientific view- 

 point, but has, too, a very decided bearing upon medical 

 practice. The general composition of the milk-fat of a 

 nurse, as pointed out by Engel 73 from systematic studies in 

 the Dresden Infants ' Home, depends upon the character of 

 the fats of the food ingested. The importance of the details 

 of diet for maintenance of health of the normal human being 

 has unquestionably been very greatly exaggerated by the 

 laity generally ; and it is of more immediate importance to 



"Willy, 1889; Stellwag, 1890; Heinrich, 1891; Klien, 1892; Lehmann, 

 1896; Winternitz, 1897; Eosenfeld, 1898; Baumert and Falke, 1898; Hen- 

 riques and Hansen, 1899; Caspar!, 1899; Engel, 1906; Gogitidse, Zeitschr. f. 

 Biol., 45, 353, 1904; 1,6, 403, 1905; 47, 475, 1906; W. Caspar! and H. Win- 

 ternitz, Zeitschr. f. Biol., 49, 558, 1907; cf. Literature in K. Basch, 1. c., and 

 A. Magnus-Levy and L. F. Meyer, 1. c., p. 468. 



"Engel ( Schlossmann's Clinic), Arch. f. Kinderheilk., 48, 194, 1906; 

 Zeitschr. f. physiol. Chem., 44, 352, 1905. 



