Dec, 1921] PATON POLLEN AND POLLEN ENZYMES 489 



due to the action of invertase. Moreover, apple pollen, which was found 

 to contain sucrose, was extremely active in its invertase reaction. The 

 results are shown in table 12. 



Table 12. Tests for Invertase 

 Kinds of Pollen Active Pollen Control 



Easter lily pollen Rapid reduction Slight reduction 



Lilium rubrum Slow 



Red maple Very rapid reduction 



Norway maple Rapid reduction 



*Apple Instant Some after 20 min. heating 



Austrian pine Slow but marked Slight reduction 



Scotch pine 



Magnolia Very rapid 



Dandelion Slow but marked 



Tests for Lipase 



In the different methods used for testing for lipolytic enzymes the fol- 

 lowing substrates and testing reagents were used : 



1. Substrates. 



(1) Ethyl butyrate. 



(2) Olive oil acidified with decinormal acetic acid and a little gum 



arabic added to make an emulsion. 



(3) Olive oil emulsion recommended by Zeller. 10 cc. of olive oil 



was dissolved in hot 100 percent alcohol. This was run through 

 a hot separating funnel to which was attached a piece of glass 

 tubing drawn out to a capillary jet. The stream of oil in alcohol 

 was run into 100 cc. of cold distilled water which was stirred 

 continually. The milky emulsion was then heated to drive off 

 the alcohol and afterwards diluted with water. 



(4) Methyl acetate. 



2. Activator. Approximately N/60 oxalic acid was used, partly because 

 free acid is needed to counteract the slight alkalinity of the ground glass 

 and more especially because free acid accelerates the activity of lipase. 



3. Alkali for titration. Approximately N/10 sodium hydroxid solution 

 was used to which a trace of barium hydroxid was added. To insure uni- 

 formity in readings, a 3-liter bottle was filled, and the solution was drawn 

 off as needed through a connected graduated burette. Both the bottle and 

 the burette had soda-lime bulbs at the inlet to absorb C0 2 . 



4. Indicator. Phenolphthalein was used in all titrations as an indicator. 



5. Antiseptic. Toluol was added as an antiseptic. Controls of auto- 

 claved pollen extract were run in each case, and the digestions were carried 

 on in small stoppered Erlenmeyer flasks kept in an electric incubator at 36 °- 

 38 C. Samples were titrated at different time intervals. Methyl acetate 

 was more strongly hydrolyzed than either ethyl butyrate or the olive oil 

 preparations. 



