96 



of much interest as well in connection with the problematic 

 morphology of the tendrils, as in showing the mode of origin 

 of the anomalous structure of the wood. Of Natiatum Jierpeti- 

 cum Ham. from Bengal my entire alcoholic material consisted 

 of a small portion of a stem 1 cm. in diameter from Kew. 

 Younger stems however in a dried state I have had from the 

 Berlin Herbarium. Of Pyrenacantha scandens Harv. of South 

 Africa I have seen only dried stems of small size also from 

 the Berlin Herbarium. These however treated with proper re- 

 agents and sectioned showed very well the most important 

 features in the structure of the wood. 



As it will often be necessary, in treating these related 

 plants, to refer to the anatomy of Phi/tocrene , and as much 

 of the interest of the following pages depends upon the com- 

 parative view of the group, a brief resume of the chief anoma- 

 lous features of Phytocrene ^) , and the special terminology ap- 

 plied to them may not be out of place. 



With the first appearance of secondary thickening in a Pliy- 

 tocrene-'&i^vix , a regular, circular cambium-ring is formed, which 

 gives off on its inner side an even, narrow ring of xylem- 

 elements, differing histologically fiom all the xylem which 

 is subsequently formed. The elements of this ring of wood 

 („E,ingholz") ^) are narrow, pitted vessels and blunt , septate 

 fibre-cells. After the ring has attained a breadth of 6 — 10 

 cells, a small amount of phloem having at the same time 

 been given off outwards, there occurs a sudden change in the 

 cambial products , and the cambium quickly loses its circular 

 contour becoming strongly lobed. This lobing is due to the fact 

 that from certain definitely situated portions of the cambium 



1) For more detailed accounts of tbe anatomy of this genus the reader may be 

 referred to Mettenius , Beitriige zur Botanik pp. 50 — 61; de Bnry, Vergl. Anat. pp. 

 591 — 3; and the author's Beitriige z. Kennt de Stammanat. v. Phytocrene macro- 

 ■phylla Bl., Botan. Zeit. Oct. 1889. 



2) With a hope of facilitating reference, the German terminology, adopted in 

 the author's description of Phytocrene macrophylla , will be occasionally given in 

 the course of this paper. 



