348 PROF. H. M. WARD AND MISS E. DALE ON CRATEROSTIGMA PUMILUM. 



slender, in others relatively thick (PL XXXV. figs. 25 & 26). In sections stained with 

 gentian violet and eosin these bodies take up the eosin. 



A transverse section of one of the large vascular bundles near the base of the leaf 

 consists of vertical rows of vessels separated by parenchymatous cells. In longitudinal 

 sections these vessels are seen to be spiral. Below the xylem is the phloem with its 

 parenchyma, the whole being surrounded by an endodermis and a pericycle. The 

 latter is interrupted on either side in the region of the phloem. No trace of internal 

 phloem could be found; the bundles are strictly collateral. The smaller vascular 

 bundles are very peculiar (PI. XXXV. fig. 27). Among the large number of leaf -sections 

 which we have examined, only one showed ordinary spiral tracheides. Their place 

 seems to be taken by thin- walled tracheides with numerous transverse shelf -like rings 

 or spiral thickenings. 



Transverse sections show that the bundles consist of one or more rows of about three 

 or five tracheides. Above each row of tracheides is usually a single cell as large as or 

 larger than the tracheides in diameter, but thin-walled and without transverse thickenings. 

 Below the tracheides, in all but the very smallest veins, are a few elements of phloem. 

 The whole is surrounded by cells arranged in a manner which suggests a sheath. Beyond 

 them are the ordinary parenchymatous cells of the leaf. 



In longitudinal section the transverse thickenings are seen to be so numerous that the 

 tracheides appear to be cut up into segments, square, or even broader than they are long. 

 Between the ordinary spiral tracheides or vessels of the larger veins and the peculiar 

 square elements are transitional forms consisting of shelf-like spirals which are more or 

 less broken up. 



The Stem is either a short thick root-stock or a creeping rhizome. It consists of a 

 central pith surrounded by a relatively thick mass of xylem and a not inconsiderable 

 phloem. The cortex contains numerous very large and irregular intercellular spaces, 

 which, except near the central stele and the path of the adventitious roots, are lined with 

 the red granules. The cortical cells, like those of the root, contain numerous leucoplasts 

 (PL XXXV. fig. 20). The bundles are open and collateral, and there is a slight 

 cambium. Surrounding the phloem is a fairly well-marked endodermis. But the 

 vascular cylinder of the stem is much broken up by the large number of adventitious 

 roots which arise in it and make their way through the cortex to the exterior. 



The Bed Colouring. matter *,— Owing to the scarcity of the material, we have only 

 been able to examine the colouring-matter microchemically and with the aid of polarized 

 light. 



The colouring-matters of plants have been investigated by various observers, among 

 others by Courchet (" Rccherches sur les Chromoleucites," Annales des Sciences Naturelles, 

 s^rie 7, p. 263). According to this author, all colouring-matters other than chlorophyll 

 and a few of very rare occurrence may be divided into two main groups : I. the cyanic 

 series, and II. the xantJiic series. 



* Reddish colouring-matters are not uncommon in roots, but they are frequently confined to the sap, or are in 

 hue, abundance, solubility, and other ways very different from the case we are considering. The reader may 

 consult, e. g., Hildebrand, Ber. d. deutsch. hot. Gesellsch. 1883, Bd. i. p. xxvii, and Ascherson, ibid. p. 498. 



