614 MILK. 



that the purified fat-globules contain a special protein substance differing 

 from the dissolved proteins of the milk is correct, then the assumption 

 as to a special body forming a membrane or stroma of the fat-globules 

 becomes very probable. The correctness of STORCH'S view has been 

 substantiated very recently by ABDERHALDEN and VoLTz. 1 On the acid 

 hydrolysis of the fat-globules they obtained glycocoll. which is absent 

 in the casein as well as in the lactalbumin, and this shows that the fat- 

 globules at least cannot contain these two proteins alone. They must 

 contain another protein, and it is still a question whether besides this 

 they also contain casein and lactalbumin. 



The milk-fat which is obtained under the name of butter consists 

 chiefly of olein and palmitin. Besides these it contains, as triglycerides, 

 myristic acid, stearic acid, small amounts of lauric acid, arachidic acid, 

 and dioxyslearic acid, besides butyric acid and caproic acid, traces of 

 caprylic acid and capric acid. RIEGEL claims that triglycerides of vola- 

 tile fatty acids do not occur, but rather mixed triglycerides of volatile 

 and non-volatile fatty acids. Milk-fat also contains small quantities of 

 phosphatides, (lecithin) and cholesterin and a yellow coloring -matter. The 

 quantity of volatile fatty acids in butter is, according to DUCLAUX, 

 on an average about 70 p. m., of which 37-51 p. m. is butty ic acid and 

 30-33 p. m. is caproic acid. The non-volatile fat consists of A-TV 

 olein, and the remainder is chiefly palmitin. The composition of butter 

 is not constant, but varies considerably under different circumstances. 2 

 According to LEMUS 3 the small fat-globules contain more olein and 

 less volatile acids than the large globules. 



The milk-plasma, or that fluid in which the fat-globules are suspended, 

 contains several different proteins, the statements as to the number and 

 nature of which are somewhat at variance. The three following, casein, 

 lactalbumin, and lactoglobulin, have been most closely studied and are 

 well characterized. The milk-plasma contains two carbohydrates, of 

 which the one, lactose, is of great importance. It also contains extract- 

 ive bodies, traces of urea, creatine, creatinine, or otic acid, hypoxanthine (?), 

 cholesterin, citric acid (SOXHLET and HENKEL 4 ), and lastly also mineral 

 bodies and gases. 



1 Zeitschr. f. physiol. Chem., 59. 



2 Riegel, Maly's Jahresber., 34; Duclaux, Compt. rend., 104. Various statements 

 as to the composition of milk-fat can be found in Koefoed, Bull. d. 1'Acad. Roy. 

 Danoise, 1891, and Wanklyn, Chemical News, 63; Browne, Chem. Centralbl., 1899, 

 2, 883. In regard to the elementary composition of milk-fat see Fleischmann and 

 Warmbold, Zeitschr. f. Biol., 50. 



3 See Maly's Jahresber., 34. 



4 Cited from Soldner, Die Salze der Milch, etc., Landwirthsch. Versuchsstation,. 

 35, Separatabzug, 18. 



