THE BRACKEN FERN. 89 



PLATE XXI. 



THE BEACKEN FEEN. EXTERNAL CHARACTERS. THE ANATOMY AND HISTOLOGY OF THE 



VEGETATIVE ORGANS. 



FIG. I. A fern plant, carefully washed after removal from the earth. 



The transverse dotted-line indicates the level of the soil, the leaf of the current season 

 ii. alone rises above it, and of those parts beneath it i. represents the leaf next to reach the 

 surface, and iii. the disintegrated base of that of last season. J nat. size. 



The arrows indicate directions of active growth. 



FIG. II. One node of a fern plant, from which a second leaf has been developed in one 

 season. 



i. The past, ii. The current, iii. The young frond. J nat. size. 



FIG. III. Transverse section across an internode of the rhizome at its thickest part. 

 The roots are not indicated. 



FIG. IV. Longitudinal section through an internode, at right angles to the lateral line. 

 It passes through the base of a lateral root. 



FIG. V. A transverse section across the youngest node, passing through the axis of a 

 young leaf. 



The smaller sclerenchyma tracts are not indicated. 



(Figs. III. to V. all x 2.) 



FIG. VI. A portion of the rhizome, from which, after two days' immersion in alcohol, 

 the superficies tissues were scraped away to the level of the bundle system. Nat. size. 



FIG. VII. Portion of a thin transverse section across the rhizome, sufficient being 

 indicated to take in one entire vascular bundle. A. 2. 



The bundle sheath, the protophloem of Eussow (138), and conjunctive parenchyma are 

 all shaded over. 



FIG. VIII. Portion of a transverse section of a vascular bundle, more highly 

 magnified. D. 4. 



FIG. IX. Portion of a radial longitudinal section of the rhizome, the same parts being 

 shaded as in Fig. VII. A. 2. 



FIG. X. Portion of a thin radial longitudinal section of a vascular bundle, passing 

 through the protoxylem. This, for the sake of distinction, has been shaded over. 

 All the vessels are here drawn as seen in surface view. D. 4, 



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