u. 



three days' r;rowth the pollen tube frequently "encyst- 

 ed", (Fig. :22) that is, a spherical s'.velling developed 

 at the tip or near the tip of the tube into which near- 

 ly all the contents of the tube v/as withdrawn includ- 

 ing one or both nuclei, when a wall was formed behind. 

 This completely closed off the swelling, which was oft- 

 en as large as the original grain. I have not deter- 

 mined the exact conditions which called forth this ac- 

 tion, neither have I found such things in the style in 

 normally grown pollen tubes. }1iss Benson ( 4 ) re- 

 ports a case of somevihat the same character as occur- 

 ring in Carpinus, though the spherical character and 

 the separating wall were not nearly so px'onounced. She 

 suggests that this may bo of xise ifi the s!iort resting 

 period of this form, but was not able to find such ap- 

 pearances in the style. 



The pollen showed ability to spro\it at room-tem- 



