114 BOTANICAL GAZETTE {AUGUST 
Description of the pollen 
The pollen grains mature very early in the history of the flower, 
the stamens and pistil being about 0.25 mm. in length and the 
integuments barely appearing on the ovules when the mother cells 
divide. When the embryo sac is mature the pollen grains are 
binucleate. They are almost globular when turgid, with a little 
flattening around the germ pores, and have an average size of 44.5 
X43. The pollen is plasmolyzed when shed from the anther, and 
one diameter is much shortened by an infolding of the wall. The 
average dimensions in this condition are 26X48 p. . 
ConTENT.—Pollen treated with chloral hydrate and _ iodized 
potassium iodide gave no starch reaction. The immediate bursting 
of the pollen in these solutions permits good exposure of the con- 
tents and makes observations easy. Treated with Sudan III, the 
numerous small particles giving the pollen content its granular 
appearance gave a definite fat reaction. This fat exists in the form 
of a fine emulsion. 
OsMotic PRESSURE.—In determining the osmotic pressure, 
sucrose solutions were used, since the pollen seems less permeable 
to this sugar. Volume-normal (mol. wt. dissolved to a liter vol- 
ume of solution) solutions were used in watch glasses, which were 
sealed to prevent evaporation and left on the laboratory table. 
The results are given in table I. 



TABLE I 
Time 1.5 2 2.33 2.5 2.66 
volume-normal | yolume-normal volume-normal yolume-normal | volume-normal 
iciedine ee 
| Turgid Plasmolyzed _| Plasmolyzed | Plasmolyzed 
20TH . « « « e 
gO TR: “ « « “i 
ihn. & « é “ “ 
“ * 
7 hrs... - 5 per cent turgid 2 . 
20 hrs. . « “ 10 per cent “a é “ 
48 hrs. . “4 “ 20 percent “ 









The table shows that a 2. 33 volume-normal solution is a little 
weak, provided the pollen grains are not permeable to the solution; 
but 2 -33 volume-normal is nearer the proper strength than 2.5. 
If 2.33 volume-normal is changed to weight-normal (mol. wt. 

LS SRE ae eae ee ee 

