100 EXPLANATION OF PLATE 62. 



most beautifully preserved, and the integuments of 

 the petiole 6, longitudinal vessels e, and gum ves- 

 sels j\ correspond with those in Fig. 1. See V. I. 

 p. 499, Note. (Original.)^^ 

 Fig. 3. Transverse section of a portion of the lowest 

 Petioles, in PL 61. Fig. 3, Z>, c, magnified four 

 times. The disposition of the bundles of vessels is 

 nearly parallel to the integument of the Petiole.f 

 d. Magnified portion of the double woody circle, within 



the Embryo bud, PL 61. Fig. 3, 'd. 

 d\ More highly magnified portion of the embryo double 



woody circle d. 

 c. More highly magnified section of one of the bundles 



of vessels, adjacent to c. 

 These bundles of vessels exhibit, in their transverse 

 Section, a series of minute tubes, arranged in rows, and 

 between these rows, opaque plates of compressed cellular 

 tissue^ resembling portions of medullary rays. 



The fibrous structure of the integument is preserved in 

 several parts of ^. See V. I. p. 501, Note. (Original.) 



* Mr. Robert Brown has noticed in the cellular tissue of a silicified 

 trunk of Cycadites, portions of Chalcedony hearing the form of ex- 

 travasated gum within the trunks of recent Cycadeae. He has also 

 recognised spiral vessels, in the laminated woody circle of a mature 

 trunk of fossil Cycadites, and also in the laminated circle within a 

 silicified hud of the same, near its origin. 



■\ A familiar example of a nearly similar disposition of bundles 

 of vessels, passing into the Petiole or leaf-stalk, may be seen in the 

 base of the fresh fallen leaves from a horse-chestnut tree, or in the 

 scars on a cabbage-stalk, from which leaves have fallen off. 



