3o. 



carpels from rain and other forms of moistiu'e. 



The pollen tubes found at this time are usually 

 of greater diameter than at the beginning of growth. 

 Tubes grown in sugar-gelatine solutions are from five 

 to eight mikrons in diameter, and those which sprout 

 on the stigma are at first approximately of the same 

 size. But those found during the resting stage are 

 fro.': twelve to fifteen mikrons in cross-section. The 

 wall is also thicker than at first (fig. 28). The nu- 

 clei found have not exceeded two in any tube. There 

 jseems some evidence from figure I? that the division 

 of the generative nucleus has taken nlace at this f^tage 



When growth is renewed in the spring the area of 

 conductuve tissue on the fimicules being increased +ne 

 pollen tube is soon seen in the cavity of the ovary. 

 More than one tube may reach the ovary. At first the 

 ovule is by no means ready for fertilization, and +he 



