244 THE SECOND BOOK OF BOTANY. 



layer of annular, spiral, or reticulated cells, which di- 

 minishes in thickness as it approaches the line of de- 

 hiscence. 



In the structure of a carpel, you find the ovary 

 covered with a double layer of epidermis, enclosing 

 cellular tissue and fibro-vascular bundles that rise 

 from the ovary into the style, not as in the filament 

 at its centre, but at the circumference. The centre 

 of the style is a sort of canal, with cells projecting 

 inward, and its middle filled with moist, cellular fila- 

 ments, called conductive tissue. This tissue also forms 

 the summit of the style, is destitute of any epidermis, 

 and is familiarly known to you as the stigma. 



The fibres of the pistil end in the placenta, which 

 gives off spiral vessels to the funiculus. These ves- 

 sels terminate in the chalaza of the ovules. Make 

 sections of these parts, and observe the structure for 

 yourselves. 



Watch the development of young leaves. Ob- 

 serve at what stage of growth the framework be- 

 comes visible ; whether the base or apex is formed 

 first ; when the stipules appear ; when lobes, and the 

 leaflets of compound leaves. How does a leaf look 

 when first visible in the bud ? Has it any thing like 

 a leaf-form? Can you find vessels or fibres in its 

 structure while yet in the bud ? 



Watch the development of the various organs of 

 the flower as the bud is growing. Observe which of 

 its organs appear first. Note whether the base or 

 apex of the petals is formed first. Where the parts 

 of the calyx and of the corolla are grown together, 

 observe whether the tube or the limb is first formed. 

 In regard to stamens, see whether the filament and 



