240 APPENDAGES OF THE AXIS [BOOK i. 



protuberance (limbus) surrounds the hole, as in the latter, but 

 this has in addition a notch at its lower part ; we then find on 

 the inner surface of the pit a ring running parallel with the 

 limb, i. e., concentric ; at the bottom of the pit a bundle of 

 woody fibres, broken off, but still somewhat projecting, like 

 the ligamentum teres'of the human acetabulum . The surface 

 of the pit between this woody bundle and the ring-shaped 

 scar is smooth, and presents nothing remarkable. As regards 

 the nature of these elegant pit-like scars, by comparing all 

 parts of the surface, we soon perceive that they owe their 

 origin to roots, which separate spontaneously; this view is 

 confirmed by tracing the course of the separation. Even 

 whilst the root is perfectly entire, the bark of the stem is 

 raised from the surface of the latter, and gives rise to the 

 above-mentioned limb. The concentric ring on the inner 

 surface of the pit is formed by the separation of the bark of 

 the root from that of the stem, and the broken-off woody 

 bundle found in the bottom of the pit was previously con- 

 tinuous with the central woody bundle of the root. (Annals 

 of Natural History, vol. xvi. p. 236.) 



For a minute account of the Root the reader is referred to 

 a paper by M. Auguste Trecul, in the Annales des Sciences, 

 3 series, vol. v. p. 340. 



SECT. IV. Of the Appendages of the Axis. 



From the outside of the stem, but connected immediately 

 with its vascular system, arises a variety of thin flat expan- 

 sions, arranged with great symmetry, and usually falling off 

 after having existed for a few months. These are called, 

 collectively, appendages of the axis ; and, individually, scales, 

 leaves, bracts, flowers, sexes, and fruit. They must not be 

 confounded with mere expansions of the epidermis, such as 

 ramenta, already described (p. 158), from which they are 

 known by having a connexion with the vascular system of 

 the axis. Formerly botanists were accustomed to consider 

 all these as essentially distinct organs ; but, since the appear- 

 ance of an admirable treatise by Goethe in 1790, On the 

 Metamorphoses of Plants, proofs of their being merely modi- 



