loo 



ing to those observed in longitudinal section, particularly noticing 

 what belongs to the Phloem, and what to the Xylem. 



This Bundle is not only a Collateral Hnndle (Bessey, p. 120), 

 but a Bicollateral I>mt<ll<', (Fig. 20) i. e., one having a layer of 

 Phloem tissue (Sieve-tubes, etc.), on the axial, as well as on the peri- 

 pheral part of the Bundle. De Bary, p. 319. 



Sketch so much of the cross-section as shall include one Bundle 

 and the tissue extending from it to the Epidermis ; also the middle 

 longitudinal section studied. The drawings should be on a scale to 

 show the characteristics of each tissue-form. 



Illustration C: RADIAL BUNDLE in the root of HYACINTH, or 

 CORN. (Figs. 16, 17, 21, 22.) 



In the transection prepared in the usual way, 



OBSERVE: 1. The central portion of the root surrounded by 

 the Endodermis, a single layer of cells easily recognized by the 

 suberized thickening of the contiguous walls. 



2. Just inside the Endoderinis, arranged in a circle, 12-18 

 groups of thick-walled cells, vessels in section. These, together 

 with the wood parenchyma, constitute the xylem of the bundle. 



3. Between these xylem areas, groups of thin-walled cells, 

 with a few large sieve-tubes in section, The Phloem of the Fibro- 

 Vascular Bundle. 



4. The large isodiametric cells of the Pith. 



Vines' Text Book of Bot., pp. 165, 168; Bessey, p. 115; De- 

 Bary, pp. 348-366; Goodale, p. 109. 



Illustration D: CONCENTRIC BUNDLES from the Khizome of 

 Pteris. 



PREPARATION FIRST: Good sections can be obtained by fasten" 

 ing some of the material, hardened in alcohol, between two pieces 

 of cork in the jaws of a microtome, and sectioning with a strong 

 razor. The material must be kept wet during the operation, and 

 after staining can be mounted directly in glycerin jelly, or after 

 dehydrating and clearing, in balsam. 



OBSERVE: \. Circular or lunar-shaped masses of whitish tis- 

 sue scattered through the preparation, The Concentri*- Handles. 



2. The well marked bundle sheath, composed of a row of 

 ellipsoidal cells. 



3. With the high power, the xylem of the bundle occupying 



