CAPSELLA BURSA-PASTORIS. 23$ 



v. The structure of the false partition, 

 vi. Draw. 



c. The ovules. 



i. In favorable sections the pollen tubes maybe 

 seen entering the ovules. These are easily 

 recognized, as the tube breaks off some dis- 

 tance from the micropyle. 

 ii. The fibro-vascular bundle of the funiculus 



terminating in the ovule, 

 iii. The two integuments, distinct from each other 



beyond the bend. 



iv. The nucellus, containing a large cavity, the 

 embryo sac, which follows the curve of the 

 ovule. Within the embryo sac 

 v. The embryo, in various stages of development, 

 vi. Draw, showing all the above facts. 

 The following phases in the development of the embryo 

 can not be seen in alcoholic specimens, but may readily be 

 traced in fresh ones by the use of potash as a clearing agent. 



d. The embryo. Mount some cleared ovules from an 

 advanced but unopened bud, press slightly upon 

 the cover glass, and note 



i. The large curved embryo sac. 



ii. In the end of the sac nearest the micropyle, a 



roundish or oblong cell, the oosphere. 

 iii. At the opposite end of the sac, a mass of 



cells projecting into it. 



Mount ovules from an open flower, treat as before, note 

 iv. In place of the oosphere a chain of cells, the 

 pro-embryo, with the basal cell usually much 

 swollen and with a group of cells at the free 

 end of the chain, the forming embryo 



10 The endosperm, which develops rapidly in angiosperms after fertili- 

 zation, is too transient in this case to make out satisfactorily. 



