26o 



PRIMARY ARRANGEMENT OF TISSUES. 



a similar one from the opposite leaf, and the united bundle (I-i-L) then curves into the 

 ring. Its course in the ring may be gathered from Fig. 115. The lower endings of the 

 bundles in the ring were not investigated. Opposite its point of exit into the leaf the 

 median bundle gives off a branch on either side, which takes a curved and almost 

 horizontal course through the cortex to the nearest angle, and here unites with the 

 out-gt)ing lateral bundle. The transverse girdle accordingly arises from the last-named 

 branches of the median bundles, and the horizontal portions of the lateral ones. From 

 the latter sections of the girdle there arise near each angle one or two cortical bundles 

 (/■), which run perpendicularly to the next lower node, and here insert themselves on 

 the transverse girdle. If two cortical bundles are present, they stand radially before one 

 another, and one often inserts itself on the other before reaching the lower girdle. 

 To the above description it may be added that the two lateral bundles which have been 

 mentioned in each leaf-trace are each formed by the coalescence of two lateral bundles 

 (/ and J), Fig. 115) of the base of the petiole. 



For further peculiarities in other species re- 

 ference may be made to A'ochting's work: it may 

 be added that the examples here selected have 

 been retained, since the corresponding woodcuts 

 were finished two years before that work appeared. 

 Species with wide wing-like projecting angles often 

 have several cortical bundles placed radially one 

 before another in each of these angles (e. g. Hete- 

 rocentron subtriplinervium, Lasiandra macrantha 

 3-4, Centradenia grandifolia 5-7), these anastomose 

 now and then with one another; they originate as 

 branches either of median or lateral bundles of the 

 first order, or from lateral bundles of a higher order, 

 if such are present. 



Besides the cortical bundles there are also 

 cauline medullary bundles in most of the Melasto- 

 maceae (compare Fig. 116). These are usually to be 

 found also in those species in which the cortical 

 bundles are absent. Only Sonerila margaritacea 

 is without either : it alone of the species investigated 

 has a quite typical Dicotyledonous bundle-system. 

 In the simplest case a single bundle is found in the 

 centre of the pith, e. g. Medinilla farinosa, Sieboldii, 

 or this may even be sometimes present, sometimes 

 absent, as in Eriocnema marmorata and Centra- 

 denia rosea. In the transverse section of the in- 

 ternode of other species there are several bundles 

 which lie in the middle of the pith, e.g. Melastoma 

 igneum, Lasiandra Maximiliani 1-3, Medinilla mag- 

 nifica 2-4, jNIelastoma cymosum 8-10 ; finally, others 

 have many of them scattered over the whole trans- 

 verse section, e.g. Heterocentrcn subtriplinervium 

 18, Miconia chrysoneura and Cyanophyllum magnificum 30, 40, and more. 



The medullary bundles run perpendicularly through the internodes. In the nodes 

 they are connected by oblique or transverse branches of varying number one with 

 another, and with the bundles of the ring. From the network or felt thus formed proceed 

 those of the next higher internode. In the large majority of cases they arise much 

 later than the bundles of the leaf-trace which are in the same transverse section, and 

 they do not pass out to the leaves. The medullary bundles are usually relatively small, 

 aid characterised by peculiarities of structure to be described below (§ 105). 



Fig. T16. — Osbeckia canescens. Tliick transverse 

 section through a node, which is rather further 

 developed than 3 and less than 2 in Fig. 115; it is 

 transparent, and seen from below. The transverse 

 sections of the bundles of the leaf-trace which are 

 nearest the beholder and in the surface of section 

 are represented as dark. ^n\ the median bunrltes of 

 the trace passing out at the node ; / the lateral 

 bundles of the same; r the cortical bundles which 

 pass down from the node; o those which pass upwards 

 from it ; ?«2 the median bundles of the next higher 

 node, which branched above the node; with them 

 there alternate, opposite each corner, single bundles, 

 with regartl to which it is not quite certain whether 

 they are the lateral ones of the next higher pair of 

 leaves, or shanks of the median bundles of the 

 second higher pair. The lighter spots in the pith 

 indicate thetransverse sections of the cauline bundles. 

 In this node they were not yet plain, and have Iieen 

 draw n in the figure from another preparation (40). 



