402 FAT-SPLITTING TISSUE FERMENTS 



estersplitting ferment present, but no lipase. We have al- 

 ready seen, too, that the apparent disappearance of fat from 

 the blood, as may be observed in vitro (v. supra, p. 370) , is due 

 to a masking of the fat but not to a lipolysis. In the course 

 of the last few years P. Eona and L. Michaelis 3 have reverted 

 to the question of cleavage of esters and fat in the blood. 

 They start out from the fact that observation of the surface 

 tension of aqueous solutions of glycerol esters permits one 

 to follow the cleavage of these substances with unusually 

 marked clearness ; the glycerolesters of the lower fatty acids 

 (in contrast to their cleavage products) belong to the sub- 

 stances having very marked surface activity which sharply 

 lower the tension of water. They were able to recognize, 

 using Traube 's drop counter, the presence not only of Han- 

 riot 's monobutyrin-splitting ferment but also of a tributyrin 

 splitting ferment in the blood. The velocity of ester cleav- 

 age was approximately in proportion to the quantity of fer- 

 ment. 4 The authors named speak of the tributyrin-splitting 

 ferment as a "true lipase," a statement which is perhaps 

 entirely correct from the standpoint of physical chemistry. 

 Whether, however, this lipase is of importance from a 

 physiological point of view, and whether it is actually to be 

 considered as involved in the cleavage of true fat can 

 scarcely be regarded as proved. An observation of Abder- 

 halden and Eona is of interest here, indicating that after 

 feeding large amounts of specifically foreign fat and, too, in 

 starvation, an exaggeration of the ester-splitting power be- 

 comes noticeable in the blood of dogs. 5 That the serum 

 lipase cannot be held to be simply resorbed pancreatic lipase 

 is shown by the points that it is not materially influenced by 

 removal of the pancreas, and that it does not seem to be at 



8 P. Rona and L. Michaelis (Hospital at Urban, Berlin) , Biochem. Zeitschr., 

 31, 345, 1911. 



4 P. Rona, Biochem. Zeitschr., 33, 413, 1911; P. Rona and J. Ebsen, ibid., 

 39, 20, 1912. 



B E. Abderhalden and P. Rona, Zeitschr. f. physiol. Chem., 75, 30, 1911; 

 E. Abderhalden and A. E. Lampe", ibid., 78, 396, 1912. 



