CELL-CONTENTS AND FORMS OF CELLS. 243 



wheat and barley, dates, bananas, mulberries, and especially in 

 the green leaves and young shoots of higher plants. In yeast it 

 is accompanied in many cases by maltase. 



EMULSINS are a class of glucoside-resolving enzymes found 

 in the seeds of the almond, the bark of Primus serotina, the leaves 

 of Prunus Laurocerasus, and in a large number of plants of the 

 Rosaceae. It is also found in the tuberous roots of Manihot 

 utilissinia, Monotropa, species of Polygala, Hedera Hclii'. 

 Enzymes resembling emulsins, and capable of attacking gluco- 

 sides, have been detected also in Aspergillus, several species of 

 Polyporus, found growing in wood, lichens, mosses, and bacteria. 

 A distinction is sometimes made between almond-emulsin, Asper- 

 gillus-emulsin, etc. 



MYROSIN, an enzyme which hydrolyzes the sulphur-glucosides, 

 occurs in the Cruci ferae and in certain species of Manihot. It is 

 localized in the seeds of cells which are rich in proteins. Its 

 presence may also be demonstrated in the mesophyll of young 

 leaves, in the pericycle of stems, and in the cork-cells of roots. 



GAULTHERASE (Betulase), an enzyme which hydrolyzes the 

 glucoside of methyl salicylate called ' Gaultherin." This is 

 present in Gaultheria and many other of the Ericaceae. It is 

 probably very widely distributed in the vegetable kingdom. (See 

 Amer. Jour. Pharm., 1898, p. 412.) 



PECTASE AND PECTiNASE.--The name Pectase is applied to an 

 enzyme that is always present in ripening fruit, and is capable 

 of converting pectose, a product insoluble in water, into a soluble 

 substance called pectin. The latter can be further decomposed 

 into a number of closely related substances, known as pectinic 

 acids, and which are usually combined with calcium. The term 

 PECTINASE is applied to the enzymes which in the presence of 

 lime coagulates the juices containing the dissolved pectinous sub- 

 stances forming the so-called fruit jellies. This reaction is con- 

 ditioned on the presence of lime and a certain equilibrium being 

 established between the enzyme and the concentrations of the acid 

 and calcium salts. Pectose originates by reason of certain changes 

 in the lamellae of cell-walls. While it occurs in appreciable quan- 

 tities in those fruits that have the properties of producing jelly, 

 it is probably very widely distributed. 



