TRILLIUM RECUR VA TUM. 2 1 3 



ii. The cndothecium, having its cells provided with 



transverse thickenings, 

 iii. The broken cells at the tips, corresponding to 



the broken cells at the middle of the base. 

 /. The base of the theca. Note 



i. The arrangement of the spiral cells, 

 ii. The median cavity and its extent. 

 g. Draw a theca in outline, and fill in a portion of the 



tissues. 

 //. The pollen spores. Note 



i. The surface of the wall, its roughness, and 

 the simple, large, round or oblong spots to be 

 seen upon some spores. 

 The wall in optical section. 

 Draw. 



Burst some spores by pressing on the cover glass. Note 

 iv. The empty outer layer of the wall, extine. 

 v. The remainder of the spore, still enveloped by 



the thin intine, roughened like the extine. 

 vi. The contents from broken spores, with minute 

 granules. 



\. The carpels. In a transverse section through the style, 

 notice 



a. The epidermis and parenchyma like that of the fila- 

 ment of the stamen. 



b. The fibro-vascular bundle with apparently no 

 phloem, elongated to embrace the cleft of the 

 stigma. 



The stigmatic surfaces, covered with papillae. 



In some of the pollen spores lodged upon the 



papillae, the developing pollen tubes may be 



detected. 



Illustrate with drawings. 



