TRILLIUM SP. I$I 



b. The stomatal slit, that extends between the guard- 

 cells and below the epidermis expands into the stomatal 

 cavity. Observe whether stomata appear on both leaf 

 surfaces. 



3. Draw small regions from epidermis of both surfaces. 

 Make a very thin transverse section of the leaf, 1 and 

 observe: 



4. The epidermal cells on both edges. Compare with the 

 surface view. 



5. Stomata. Find in the thinnest part of the preparation 

 a section truly transverse to the guard-cells and compare 

 with surface view. Observe the stomatal cavity between 

 and below the guard-cells, and note its relation to : 



6. The mesophyll tissue. In this region observe: 



a. The palisade mesophyll of compact columnar cells with 

 ends outward. 



b. The spongy or loosely arranged mesophyll below the 

 palisade tissue. 



7. Cross-section of veins of the leaf enclosed by the mesophyll. 

 Identify, from comparison with the stem, the tissues in the 

 vein. 



8. Draw a part of the section. 

 V. REPRODUCTION. 



i. The stamen, microsporangia, and microspores (pollen). 

 In a cross-section of a young anther observe: 

 a. The four sporangia in which are spores in process of 



development. 2 

 In a cross-section of a ripe anther observe: 



1 This will be far more satisfactory if made with a microtome. 



1 By means of material ranging in age from that of very young flower- 

 buds to buds nearly ready to open, it is possible to make out an interest- 

 ing and instructive series in the process of spore development. Still 

 younger buds will show interesting stages in the development of the 

 sporophylls. 



