Dec, 1921] PATON POLLEN AND POLLEN ENZYMES 485 



Formula for Stock Agar 



Di billed water 1 ,000 cc. 



Magnesium sulphate 0.5 g. 



Di-potassium hydrogen phosphate 1.0 g. 



Potassium chlorid 0.5 g. 



Ferrous sulphate o.ig. 



Agar 2.0 g. 



The pollen tubes grew exceedingly well in the film of moisture formed 

 on the surface of agar in petri dishes. The tubes were thicker, appeared 

 more vigorous, and showed protoplasmic movement better than when grown 

 in water or in dilute sugar solutions. This might be used as a method of 

 showing variation in cell turgescence according to the density of the medium. 



Formula for Knop's Solution 



K2SO4 0.7 g. in 1 liter of water 



NaCl 0.23 g. 



CaS0 4 0.7 g. 



MgS0 4 0.5 g. 



Na 3 P0 4 0.5 g. 



NH4NO3 (solution 0.0649) 20 cc. 



The tubes grew best in solutions from which the K 2 S0 4 was omitted, 

 and best of all in one in which the CaS0 4 was increased to 1.0 g. The 

 K0SO4 seemed to cause disintegration of the tubes after 48 hours, but this 

 evidence is of course very slight and more experiments must be tried to 

 prove anything. 



Of the four media used, tap water was selected as the best for Easter 

 lily pollen. The grains germinated and produced long tubes in 24 hours, 

 and the solution contained no foreign matter to be taken into consideration. 

 After the tubes were well grown the pollen mass was filtered and dried in 

 a desiccator. This dried germinated pollen was used both un ground and 

 ground with powdered glass. 



Comparative quantitative determinations of the enzyme action of the 

 unground, ground, and germinated pollen were made as follows: Having 

 previously noted the marked invertase action of Easter lily pollen on cane 

 sugar, the amount of copper precipitated from Fehling's solution by the 

 reducing sugar formed was taken as an index of enzyme action. 



The tests were made in five test tubes as follows: In each tube were 

 placed 300 mg. of cane sugar, 15 cc. of distilled water (except in tube 4, 

 where 10 cc. was used), and 8 drops of toluol. To tubes 1, 2, and 3 were 

 added respectively 300 mg. each of unground, ground, and ground germi- 

 nated pollen. To tube 4 was added 300 mg. of pollen boiled in 5 cc. of 

 water, making the total quantity the same as in the other tubes. Tube 5 

 had no pollen added and served as a second control. 



These tubes were allowed to stand in a warm room for 24 hours and 

 were shaken occasionally. After this interval, 15 drops of each of the five 



