A VENA SATIVA. 179 



0. The early stage of the young plantlet of 

 the seed, the embryo. 



1. Illustrate with diagram. 



Compare with this flower the second and third flowers of 

 the spikelet. Note, in the latter, the absence of the inner 

 organs, leaving only the flowering glume, palet, and some- 

 times the stamens. 



F. THE FRUIT. Study ripe oats which have been 

 threshed or shelled out in the hand. Strip off the chaff 

 (flowering glume and palet) which incloses the fruit. Note 



1. The white hairs which cover it, especially at the upper 

 end. 



2. The longitudinal groove ; its position as to the palet. 



3. The scar at the base of the grain opposite the groove, 

 marking the position of the plantlet within. 



Cut across the middle of a grain, and note 



4. The depth of the groove, and the uniform floury 

 contents ; test with iodine. 



5. That the wall of the ovary and the coats of the ovule 

 have become so closely united and thin as to be indis- 

 tinguishable, thus constituting the fruit a caryopsis or 



grain. 



6. Draw the section. 



From a soaked grain carefully remove the " skin " (the 

 wall of the ovary together with the seed coats) on the side 

 opposite the groove, from the lower end to the middle. 

 There will then be seen a face view of 



7. The embryo. Note 



a. The large elongated-triangular body forming the 



