DIGESTION 259 



seed is inoperative under these conditions. Too much 

 stress must not, however, be laid upon this point, as the 

 enzymes have not been prepared in any case in anything 

 like a pure condition. 



Eecently Vines has found that members of the ereptase 

 class are very widespread in plants, occurring in almost all 

 parts of them. His researches suggest that possibly the 

 so-called tryptases are mixtures of peptase and ereptase. 



The action of all these proteoclastic enzymes is probably 

 one of hydrolysis, though it is difficult to prove it by analysis. 



Kennet occurs in many seeds, in some cases in the germinat- 

 ing, and in others in the resting, condition. It has also a 

 wide distribution in the vegetative and floral parts of various 

 plants. Whether it is really proteoclastic in the vegetable 

 organism is hard to say, as the details of its action are 

 unknown. It is so in the animal body. 



The enzymes which decompose glucosides, as we have 

 already seen, are numerous and varied in their distribution, 

 occurring in various fungi and lichens as well as in the higher 

 plants. Their action may be illustrated by the behaviour 

 of emulsin, which exists in quantity in the seeds of the bitter 

 Almond and in the vegetative parts of the Cherry-laurel 

 (Prunus Laurocerasus) . It splits up the glucoside amygdalin 

 according to the equation 



C 20 H 27 NO n + 2H 3 = C 7 H 4 + HCN + 2(C 6 H 12 6 ) 



Amygdalin Benzole Prussic Glucose 



aldehyde acid 



This is, as in other cases, a process of hydrolysis. Myrosin, 

 another of the group, is peculiar in that it effects its character- 

 istic decomposition without causing the incorporation of 

 water during the process, thus : 



o = C 3 H 5 CNS + C 6 H 12 6 + KHS0 4 



Sinigrin Sulpho-cyanate Glucose Potassium- 



of allyl hydrogen- 



sulphate 



Other, such as rhamnase, existing in the seeds of Ehamnus 

 infectorius, erythrozym in the Madder, gaultherase in the 



17 * 



