1 90 FIELD OATS. 



c. The optical section of the wall ; its continuity inter- 

 rupted at the protuberance. 



d. The contents. Burst some spores by pressing 

 lightly on the cover-glass with a needle. Note 



i. Here and there entirely empty bursted sacs, 

 the extine. Notice the minute roughening 

 of the surface ; the thin spot or opening, 

 through which in some cases when unburst the 

 intine protrudes. 



ii. The contents of some spores surrounded by the 

 intine t escaped from the extine and become 

 much larger. In some cases the protuberance 

 may still be seen. 



iii. The contents of other spores free in the water 

 of the slide, showing innumerable fine gran- 

 ules. Note their shape, and treat with iodine 

 to determine their nature. 



e. Draw an uninjured spore, showing its structure. 



4. The styles and stigmas. Cut off one of the styles near 

 its attachment. Mount and examine with a low 

 power. Note 



a. The tapering style with 



b. Numerous undivided branches, the stigmas, 

 roughened with innumerable points. 



c. The grains adhering to the stigmas. 

 Examine with a high power. Observe 



d. The thin-walled nucleated cells, forming the stig- 

 mas ; the proximal ends are overlapped by other 

 cells. 



e. The adherent grains. Notice that some of the 

 spores have emitted through the perforation in 

 the extine a slender tube which penetrates the 

 stigma. Notice that the granules of the pollen 



