_ 96 - RESPIRATION, 



55. Lenticels, through which the respiratory gas exchange of stems takes place. 



(a) Seen with the naked eye. 



(b) Microscopic section. 



FERMENTATION. 



56. Action of invertase secreted by yeast. Saccharose is added to each of three 

 test-tubes containing : 



(a) Filtrate from a suspension of yeast in water. 

 (6) Distilled water. 



The test-tubes are placed in the incubator at 32 C. for 10 minutes and then Fehling's 

 solution is added to each and the contents heated. 



