A NOTE ON THE CHOLESTERIN-ESTERS OF 

 BIRDS' BLOOD.* 



BY ERNEST W. BROWN. 



THE interesting investigations of Hurthle f have demonstrated 

 that cholesterin occurs normally in combination with fatty 

 acids in the blood-serum of mammals. It has been pointed out 

 that the failure to recognize these cholesterin-esters has been 

 due to the methods employed in the search for cholesterin. 

 Thus the customary procedure has been to saponify ether 

 extracts of animal tissues and fluids with alcoholic potash for 

 the purpose of transforming any fats present into soaps, and 

 in this way permitting a more successful subsequent separation 

 of cholesterin by means of ether4 The method obviously 

 precludes the possibility of obtaining cholesterin-esters as 

 such. By avoiding the saponification, however, Hiirthle has 

 succeeded in demonstrating the presence of cholesteryl oleate 

 in the blood-serum of the dog, sheep, pig, ox, and horse, 

 and in the lymph obtained from the thoracic duct of the dog. 

 Cholesteryl palmitate was also obtained, although in much 

 smaller quantities; while cholesteryl stearate could not be 

 isolated. The quantities of the cholesterin-esters present in 

 the blood were approximately determined as follows: 



Cholesteryl Oleate. Cholesteryl Palmitate. 



Horse .... 0.08 per cent 0.006 per cent 



Calf 0.09 " 0.008 " 



Dog 0.12-0.22 " 



The percentage of eholesteryl oleate was observed to vary in 

 the dog with the condition of the animal, being increased 

 during hunger. 



* Reprinted from the Amer. Jour, of Physiol. vol. ii. 

 t Hiirthle, Zeitschrift f. physiol. Chemie, 1896, xxi, p. 331. 

 $ Cf. Hoppe-Seyler, Medicinisch-chemische Untersuchungen, 1866, p. 143. 

 Cf. Hoppe-Seyler, loc. cit., p. 146; Schulz, Fr. N., Arch. f. d. ges. Physiol., 

 1896, IXT, p. 299. 



