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CARNEGIE INSTITUTION OF WASHINGTON. 



ciates have led him to the same conclusion and to name these hypo- 

 thetical compounds fat-soluble A and water-soluble B. The existence 

 of such substances, which was first indicated by Hopkins, and subse- 

 quently by many others, notably Funk, who named them vitamines, 

 is now generally recognized, and it is almost universally accepted 

 that they are widely distributed among our ordinary articles of food. 



Milk appears to contain all of such substances required for both 

 maintenance and growth, and under conditions which appear more 

 favorable for future attempts to determine their nature than those 

 presented by other food products. It has thus seemed to be advis- 

 able for us to attempt to learn as much as possible of the properties 

 of all substances which we can isolate from milk, even in minute 

 proportion. Although most of these will doubtless prove to be of 

 quite subordinate importance in nutrition, a definite and precise 

 knowledge of their amount and properties will greatly facilitate the 

 search for other substances. 



The subject of our first paper dealing with the constituents of 

 milk related to the presence of phosphatides in this important food 

 substance. We have since determined the distribution of these 

 phosphatides among the various fractions into which milk is separated 

 in our process of making "protein-free milk." 



A previous examination of butter fat, centrifuged at high speed, 

 showed the presence of so small a trace of phosphorus that this fraction 

 may be considered to be practically free from phosphatides. Our 

 present investigation of the "protein-free" milk, i. e., the fraction from 

 which fat and protein had been removed as completely as possible, 

 failed to yield an}* trace of phosphatides which could be extracted 

 either by alcohol or chloroform. It thus appears that this class of 

 substances is only associated with those fractions which contain protein. 



Distributimi of Fhos-phaiides in One Liter of Whole Milk. 



Together with these phosphatides, alcohol extracts from "lactal- 

 bumin" a larger quantity of fat-like material which we have not yet been 

 able to investigate. Since the solutions from which the lactalbumin was 

 separated by coagulation are practically water-clear, it seems hnprob- 

 able that these contain appreciable quantities of the higher fats, 

 unless the latter are in some form of combination which is soluble in 



