232 ENZYMES 



Trypsins are also met with in the leaves, stems and developing 

 fruits of many plants where they facilitate the rapid translocation 

 of proteids in such organs. 



3. The power which parasitic and saprophytic plants possess 

 of absorbing and utilising as food the starch, proteins and various 

 organic materials belonging to other plants, is dependent to a 

 large extent upon their power of secreting diastatic and other 

 enzymes. 



Certain parasitic fungi penetrate into the tissues of their 

 victims by secreting an enzyme which is capable of dissolving 

 the obstructing cell-walls. 



The production of alcohol from sugar by yeast is apparently 

 effected by an enzyme named zymase, which is present in the 

 yeast-cells, and some of the chemical changes brought about by 

 bacteria are the result of the action of enzymes secreted by 

 these organisms. 



Ex. 134. — Germinate some barley grains on damp blotting-paper ; when 

 the plumule just appears taste the endosperm and compare its sweetness with 

 that of a soaked ungerminated grain. 



Compare the taste of malt with that of ordinary barley grains. 



Ex. 13B. — Prepare some thin starch-paste and a solution of malt-diastase 

 as described in Ex. 86. 



Take two tubes of starch-paste and into one pour some of the diastase- 

 soldtion, and into the other some of the same solution after it has been 

 boiled three minutes and then cooled. Test with iodine for starch in both 

 tubes every five minutes as indicated in Ex. 86. What has been the effect 

 of boiling the diastase solution ? 



