CHEMISTRY OF MILK-SECRETION. . 669 



of the gland have not given any clue as to the mode of formation of 

 casein. The findings of MANDEL l that the hydrolytic cleavage products 

 of the nucleoprotein from the mammary glands occur approximately 

 quantitatively in the same proportions as in casein, are important in this 

 connection. 



That the milk-fat is produced by a formation of fat in the protoplasm, 

 and that the fat-globules are set free by their destruction, is a generally 

 admitted opinion, which, however, does not exclude the possibility that 

 the fat is in part taken up by the glands from the blood and eliminated 

 with its secretion. That the fats of the food can pass into the milk 

 follows from the investigations of WINTERNITZ, as he has been able to 

 detect the passage of iodized fats in the milk, and these observations 

 have been substantiated by the investigations of CASPARI and PARASCHT- 

 SCHUK. 2 The abundant quantities of iodized fat which were eliminated 

 with the milk in these cases without doubt depend, at least in great part, 

 upon the iodized fat of the food, hence it cannot be said that all of the 

 milk-fat containing iodine was unchanged iodized fat of the food. The 

 previously-mentioned older investigations of LEBEDEFF and ROSENFELD 

 and also the recent ones of SPAMPANI and DADDI, PARASCHTSCHUK, GOGI- 

 TIDSE and others on the passage of foreign fats into the milk also indicate 

 the passage of the fat of the food into the milk, although we are still uncer- 

 tain on this point. According to SOXHLET the fat of the food does not 

 pass into the milk directly, but is destroyed in place of the body-fat, 

 which then becomes available and is, as it were, pushed into the milk. 

 HENRIQUES and HANSEN could not detect any mentionable quantity of 

 linseed-oil in the milk after feeding with this oil; the milk-fat was not 

 normal, but had a higher iodine equivalent and a higher melting-point, 

 from which they also concluded that a transformation of the food-f^t 

 in the glandular cells is possible. The results of the experiments of 

 GOGITIDSE 3 with soaps also indicate that the mammary glands have the 

 property of forming fats by synthesis from their components. As a 

 formation of fat from carbohydrates in the animal organism is at the 

 present day considered as positively proved, it is likewise possible that 

 the milk-glands also produce fats from the carbohydrates brought to 

 them by the blood. It is a well-known fact that an animal gives off 

 for a long time, daily, considerably more fat in the milk than it receives 



1 Bioch. Zeitschr., 22. 



2 Winternitz, Zeitschr. f. physiol. Chem., 24; Caspari, Arch. f. (Anat. u.) Physiol., 

 1899, Supplbd. and Zeitschr. f. Biologic, 46; with Winternitz, ibid., 49; Paraschtschuk, 

 Chem. Centralbl., 1903, 1. 



3 Lebedeff, Pfliiger's Arch. 31; Rosenfeld, Ergebn. d. Physiol. 1 and 2; Spampani 

 and Daddi, Maly's Jahresber., 26; Henriques and Hansen, ibid., 29; Gogitidse, Zeitschr. 

 f. Biologic, 45, 46, and 47. See also Basch/Ergebnisse d. Physiol., 2, Abt. 1. 



