CYTASES 201 



have established the fact that the hepatic secretion of certain 

 molluscs and crustaceans contains a very effective cellulose- 

 solving ferment, a "cytase." If, for instance, the liver 

 secretion of a Weinberg snail is allowed to act on a thin 

 section of the starchy endosperm of a grain of wheat it will 

 be apparent that the cell membranes are rapidly dissolved 

 even before the enclosed starch granules are visibly affected. 

 The energy with which the gastric secretion of the snail dis- 

 solves the thick and very resistive cell walls of date seeds, 

 ivory nuts or coffee-beans is still more striking. It has been 

 ascertained, moreover, that the various celluloses and hemi- 

 celluloses are broken down into the same cleavage products 

 (glucose, mannose, galactose, pentoses, etc.) by the action of 

 cytase, as occur from the cleavage from boiling with mineral 

 acids. There is, therefore, a real hydrolytic cleavage in 

 operation. The statements of Biedermann have been fully 

 confirmed by a series of control tests, 22 especially by French 

 authors. 23 



The expectation that an analogous ferment might be found 

 in the intestine of vegetable eating animals has not been 

 realized. The mammalian intestinal contents, carefully 

 sterilized by being passed through a Berkefeld or similar 

 filter, has always been found inactive for cellulose. 24 If the 

 cellulose be protected by the addition of sugar which many 

 bacteria, particularly anaerobic forms, prefer as their 

 source of energy above any other material, the cellulose does 

 not undergo cleavage, a result which would scarcely be ex- 

 pected if we were actually dealing with a hydrolytic cleavage 

 from cytases. 25 



22 E. Miiller, Pfluger's Arch., 85, 619, 1901. 



23 H. Bierry, J. Giaja, M. Pacau<t, G. SeillSre and others in C. R. Soc. de 

 Biol.; H. Bierry and J. Giaja (Sorbonne, Paris), Biochem, Zeitschr., 40, 370, 

 1912. 



34 A. Scheunert, Zeitschr. f. physiol. Chem., 48, 9, 1906; and the experi- 

 ments of Ellenberger, V. Hofmeister, Holdefleiss and H. T. Brown, cited by 

 Scheunert in Handb. d. Biochem., 3" 135, 1909. 



25 H. v. Hosslin and E. J. Lesser (Physiol. Inst. and Med. Clinic, Halle), 

 Zeitschr. f. Biol., 64, 47, 1910. 



