724 PART IV. THE PHYSIOLOGY OF PLANTS. 



1. Conversion of starch into sugar (amylolytic enzyme, commonly termed 

 diastase) : 



Starch. Maltose. Dextrin. 



3 (C 6 H 10 5 ) + H 2 = C 12 H 22 O n + C 6 H 10 5 



2. Conversion of cane-sugar into grape-sugar (invert enzyme) : 



Cane-sugar. Dextrose. Lsevulose. 



C 12 H. 22 O n + H 2 = C 6 H 12 6 + C 6 H 12 6 



3. Action of fat-enzyme : 



Olein. Oleic acid. Glycerin. 



C 5 7H 10 40 6 + 3H 2 = 3C 18 H 34 2 -f C 3 H 8 3 



4. Action of glucoside-euzyme; the instance takeu is the decomposition of 

 the glucoside amygdalin in the Bitter Almond by the ferment termed synaptase 

 or emulsin : 



Anngdalin. Oil of bitter almonds. Prussic acid. Glucose. 

 C 20 H 27 NO n + 2H 2 = C 7 H 6 + HCN + 2(C 6 H ]2 6 ) 



It will be noted that, in every case, the action of the ferment involves the 

 taking up of one or more molecules of water. 



The action of the enzymes which act on proteids (proteolytic enzymes) can- 

 not be represented by equations, inasmuch as no formulae for the various 

 proteids have at present been arrived at. It may be generally stated that their 

 effect is, like those of the other forms, to induce decomposition with the assump- 

 tion of water. The proteolytic ferments, acting some in an acid medium, others 

 in an alkaline, convert the more complex proteids, such as globulins, into the 

 simpler peptone ; and further cause the decomposition of peptone into amides, 

 such as asparagin, leucin, and tyrosin. 



The chief importance of the unorganised ferments in the 

 economy of the plant is that by their means the reserve materials, 

 which are accumulated to such a large extent in the form of 

 substances, such as starch, fat, cellulose, proteids of aleuron- 

 grains, which are either not soluble in water, or if soluble are 

 only slightly diffusible, are converted into substances, such as 

 amides and certain sugars, which are both readily soluble and 

 diffusible, and which can therefore travel osmotically from one 

 part to another. For instance, as mentioned above, the excess of 

 carbohydrate formed in the leaves when they are actively assimi- 

 lating, is commonly stored up in the form of starch. This carbo- 

 hydrate is eventually conveyed to other parts of the plant ; but, 

 since starch is insoluble, it cannot be conveyed in that form it is, 

 in fact, converted into maltose by an amylolytic ferment present 

 in the leaves, and it is in this form that non-nitrogenous organic 

 substance is conveyed away from the leaf where it has been 

 produced. Other striking illustrations of the importance of 

 ferment-action are to be found in the chemical changes going on 

 in germinating seeds, bulbs, tubers, etc. When a starchy seed, 



