A VENA SATIVA. 191 



spore also enter this tube. Observe that some 

 spores have become empty. 



f. Draw, showing structure of stigmas and the 

 entrance of a pollen tube. 



5. The trichomes of the wary. Cut off, mount, and 

 examine with a high power some of the trichomes which 

 clothe the apical portion of the ovary. Note shape and 

 contents. Draw. 



E. THE FRUIT. Remove the chaff from a grain, and 

 cut a transvense section near the middle, having previously 

 soaked it in warm (not hot) water for a few minutes. 13 

 Note 



1. While mounting, the abundant whitish powder which 

 escapes into the water, clouding it more or less. 



Examine with a high power and note 



2. The outermost coat of the fruit, the ovary wall, some- 

 times splitting into two layers ; the cells can only be 

 made out with great difficulty. 



3. The layer of large cells, containing granular proteid 

 matters, chiefly gluten. Note shape, and test contents 

 with iodine. Draw. 



4. The large cells packed with granules of starch, made 

 blue by the iodine. The outline of these cells is best 

 seen when the starch has escaped from them. 



5. The tip of the embryo will usually appear at one side of 

 the section. 



Cut a median longitudinal section through the groove of 

 a soaked fruit. Treat with potash to clear up the embryo, 

 and examine with a low power. Note 



13 An immersion of an hour or longer in cold water will answer the 

 same purpose. 



