VIII.] THE BEAN-PLANT. 85 



left hand. Moisten it with a drop of water and then 

 make with a wetted razor several successive cuts 

 through it. This will divide the stigma into several 

 slices. Spread these out on a glass slide with a 

 needle in water and examine the thinnest, after put- 

 ting on a covering-glass. 



The triangular grains of pollen will be seen sending 

 out from one angle a tube into the stigmatic tissue, 

 which is easily seen from its slight difference in 

 colour. 



2. The entrance of the pollen-tube into the micropyle 

 can be readily made out in some species of Veronica. 

 The common V. Serpyllifolia often to be found in 

 shady places on lawns is well adapted for the pur- 

 pose. A flower should be taken from which the 

 corolla has just dropped. Dissect out the minute 

 ovary and using the dissecting microscope open with 

 a needle one of its two cells in a drop of water ; 

 remove the mass of ovules and gently tease them 

 apart. Then put on a covering-glass and examine 

 with a low power till an ovule is found which shews 

 the entry of the pollen-tube. The addition of dilute 

 glycerine will make the ovule more transparent so 

 that after some time the embryo-sac can be seen and 

 the progress of the pollen-tube into the ovule followed. 



3. The young fruit of Campanula (especially the com- 

 mon Canterbury Bells of gardens, Campanula Medium) 

 is convenient for examining the embryo-sac. It is 

 only necessary to cut thin transverse sections of the 

 fruit and examine in water. Some of the ovules cut 

 through will allow the embryo-sac to be seen, and in 

 fortunate sections the embryo- vesicle and the end of 

 the pollen-tube in contact with the embryo-sac. 



