Formed Constituents of Organisms 157 



enzymes in the general protoplasm. In all the important 

 groups of the Invertebrata and Vertebrata, it is secreted either 

 by special glands — the salivary glands — when it has often 

 been called ptyalin; or it may be secreted along with other 

 ferments from some part of the alimentary canal, or of glands 

 associated with the mid region of the canal. 



Inulase, trehalase, invertase, glucase, and cytase are all 

 closely related ferments to diastase, and effect digestion of 

 inulin, trehalose or fungus sugar, cane sugar, cellulose, etc. 

 All of them occur in at least some of the fungi, and even two 

 or three may be secreted by the same plant for different lines 

 of digestive action. They have been little looked for as yet 

 amongst the moss and fern alliances, but flowering plants 

 frequently yield all of them, except perhaps trehalase. 



For the digestion and utilization of the oils that are elab- 

 orated directly, or often subsequently stored in quantity both 

 in plants and animals, a ferment that may appropriately be 

 called lipase is secreted. It has been separated from some 

 of the fungi, and is traceable up into the flowering plants, 

 where it abounds in germinating oily seeds like those of castor- 

 oil, hemp, and poppy. It is the active agent for oil digestion 

 from the sponges up to man. As shown by the subjoined 

 equation it causes stearin fat to take up water (as is true of 

 nearly all cleavage ferments), and then splits the whole into 

 glycerin and stearic acid. 



C3H5(Ci8H3502)3 + 3H20= C3H5(HO)3 + 3(Ci8H35H02) 



stearin water glycerin stearic acid 



Mention is made below of that widely distributed group 

 of chemical bodies, the glucosides, which probably result from 

 splitting up of proteids. But the glucosides are in turn decom- 

 posed by a series of ferments, and yield glucose as one of the 

 decomposition products. Hence the name given to the series. 

 Emulsin or synaptase acts on a range of related glucosides, 

 and splits these as follows in the case of amygdalin contained 

 in seeds of the almond: 



C2oH27NOn + ^20= QHgO + HCN + ^(CeHioOe) 



amygdalin water benzoic prussic glucose 



aldehyde acid 



In salicin, the simpler glucoside contained in willows, the 

 action is as follows: 



C13H18O7 + H2O = C7II8O2 + CcHiaOg 



salicin water saligenin glucose 



It has already been found in many fungi, and in diverse 

 families of flowering ])lants, so that its presence in many others 



