Dec, I92I] PATON — POLLEN AND POLLEN ENZYMES 485 
Formula for Stock Agar 
Distilled water 1,000 cc. 
Magnesium sulphate 0.5 g. 
Di-potassium hydrogen phosphate i.o g. 
Potassium chlorid 0.5 g. 
Ferrous sulphate o.i g. 
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 I liter of water 
NaCl 0.23 g. 
CaS04 0.7 g. 
MgS04 0.5 g. 
Na3P04 0.5 g. 
NH4NO3 (solution 0.0649) 20 cc. 
The tubes grew best in solutions from which the K2SO4 was omitted, 
and best of all in one in which the CaS04 was increased to i.o g. The 
K2SO4 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 enz3^me 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 
