PHANEROGAMIA : AXIAL ORGANS. 



163 169 



253 



170 



in places (at the nodes ?) the woody masses merge partly into each other, 

 while the separation occurs again in a different mode of distribution. 

 Finally, the most astonishing phe- 

 nomena are seen in the families 

 of the AristolochiacecB (fig. 170.), 

 Asclepiadacece, Malpighiacece, and 

 the BauhinicB (fig. 171.), in 

 which, in the transverse section, 

 the woody mass appears divided 

 in the strangest ways by cortical 

 substance, separated into various 

 portions, and often elegantly 

 lobed. A great part of these 

 aberrant forms of stem were 

 brought home by Gaudichaud 

 from his voyages, and he has 

 represented most of them in a 

 very negligent manner in his 



superficial book. A. de Jussieu has made better use of these mate- 

 rials, having inserted a most excellent investigation of the Lianes in 

 his monograph of the Malpighiacece, in which he has, by ingenious use 

 of the few materials for the history of development that were at his com- 

 mand, at least traced up these singularities to the general type of the 

 Dicotyledons. I pass by here a few other abnormal conditions, as, for 

 instance, the Phytocrene, described by Wallich (PI. Asiatics rariores), 



168, 169. Transverse sections of stems from the family of Sapinrfacea>, natural size, 

 a, 6, Woody masses, wholly separated by bark from the main stem (c). In fig. 168. 

 these are homogeneous throughout ; but in fig. 160., on the contrary, arranged radially 

 around a cellular tissue occupying the middle, intermediate in character between pith 

 and medullary ray cells. 



168 The annual rings are wanting in the central portion, as in the three peripherical 

 masses : the medullary rays are not very striking, and run in waving lines. The peri- 

 pherical portions have points (in one lying excentrically) from which medullary rays 

 pass out, but are without trace of pith. 



169 Here, also, the crescentic marks in the five peripherical wood-masses are the 

 places whence medullary rays set out ; but these places are not composed of cellular 

 tissue : the linear arrangement of the wood-cells is continued through them, and even 

 porous tubes occur in the middle of them. The lines, however, in which the wood- 

 cells lie, make a slight curve at their entrance and exit from the crescentic mark ; and 

 thus this originates as a mere optical phenomenon. 



170 Aristolochia biloba. Transverse section of the stem, a, Considerably developed, 

 deeply torn cork, magnified about four times. 



