and Laboratory Methods. -<J95 



3. Carefully separate the ovularies of the carpels of an orange {Citrus aiiran- 

 tium L.) so that they will lie side by side in a row. Draw. Note that some of 

 the divisions are smaller than the normal. There is a struggle for existence 

 among the members of the gynoecium so that some are not fully developed. 



4. Make a comparison of the three fruits studied above. 



LXXXVIII. Section of Sunflower Leaf. 



1. Cut cross sections of the lamina of a sunflower {Helianthus annuus L.) 

 leaf preserved in alcohol, mount, and study under low and high power. 



2. Draw and describe, showing the following tissues: upper epidermis with 

 thick cuticle and multicellular hairs, palisade parenchyma, spongy parenchyma 

 with large intercellular spaces, sections of vascular bundles, and lower epider- 

 mis with stomata and multicellular hairs. 



3. How do you account for the palisade arrangement of the cells in the 

 upper part of the leaf ? 



LXXXIX. Leaf J'ariation. 



1. Obtain a series of fresh or pressed leaves of the red mulberry (Morus 

 rubra L.) or of the giant ragweed {Ambrosia trifida L.) and make outline 

 sketches of ten different forms. 



XC. Section of Winter Bud. 



1. From alcoholic material cut longitudinal sections of common lilac buds 

 {Syringa vulgaris L.). Mount and sketch under low power. Note the flat apex 

 with outer dermatogen and hypodermal meristematic tissue ; and a little farther 

 down the epidermis, cortex (periblem), procambium (formative tissue of vascular 

 bundles), and the central pith. 



2. Note the origin of the leaves, beginning at the apex, and also the origin 

 of the lateral buds in the axils of the leaves. Make a sketch showing the entire 

 upper part of the bud, with all the structures mentioned above. 



XCI. Mo?iocotyl Stem. 



1. Cut cross sections of young corn stems preserved in alcohol, stain and 

 mount ; or use prepared slides. Sketch the entire section under dissecting 

 microscope, showing epidermis, band of sclerenchyma, large pith or ground tissue, 

 and the scattered vascular bundles. 



2. Under high power draw one of the bundles. Note the large vessels sit- 

 uated in the xylem arranged like a letter V, the cavity in the tissue at the apex 

 of the V, the bundle of phloem between and beyond the two large vessels, and 

 the sheath of sclerenchyma about the bundle. 



XCI I. LLerbaceous Dicotyl Stem. 



(a) Sunflower Stem. 



1. Cut cross sections of a young sunflower stem preserved in alcohol, mount, 

 and stain ; or study prepared slides. 



2. Sketch the entire section under dissecting microscope, showing cortex, 

 circle of vascular bundles, and large central pith. 



