450 ME. W. C. AVOESDELL ON THE COMPAEATIVE 



secondary thickening, one of which has inverted orientation, i. e., with its xylem directed 

 onticords, and which, if traced to another level, is seen to fuse with the central cylinder. 

 The strand on the other side eventually fuses with the large semi-concentric one. 

 Further out in the cortex are scattered other much smaller bundles with inverted 

 orientation {cs^}. Another group of three bundles was observed, with their xylem^ 

 mutitally directed toicards each other {cs^). 



All these smaller strands I regard, with the larger one above described, as being 

 cauline in origin, both on account of their peculiar orientation and grouping, and the 

 fact that no leaf -bundles exhibiting the normal orientation and course are present in the 

 cortex of this transitional region, but only first make their appearance at a higher level. 



All these cauline strands are found only in this transitional region between stem and 

 root, and are both above and below this region no longer to be met with, l^he great 

 importance of this point will be fully dealt with later on. The large strand is, as 

 in 3Iacrozamia Denisonii, E. MuelL, probably continuous in both directions with the 

 central cylinder, as also, in all likelihood, is the case with the smaller normally-orientated 

 strands immediately abutting on its dorsal side. But, unfortunately, not one of these 

 strands was distinctly traced throughout its whole course. 



At the same level at which these cortical caiiline strands appear, the central cylinder 

 at one point exhibits a most peculiar anomaly, inasmuch as it there undergoes a curious 

 invagination, so that an arc of bundles, all more or less intimately united laterally, is seen 

 projecting into the pith. 



An outer vascular zone has not yet arisen in this stem similar to that in the last 

 species. But there cannot be much doubt that the strands above described represent 

 the first beginning, although on one side of the stem only, of the outer vascular zones, 

 each strand representing in reality a single segment of a whole ring. 



At a somewhat higher level the leaf-trace bundles appear in the cortex, so that it is 

 possible, what could not be certainly made out from the structure of the central cylinder, 

 that the region below this level belongs to the root rather than to the stem, although 

 mucilage-canals are there present both in pith and cortex, and medullary bundles are 

 also abundant. 



The tap-root is exceedingly thick and swollen in one portion of its length, so that the 

 xylem becomes broken up by the expanding parenchymatous tissues into a large number 

 of scattered fragments. 



Encephalartos lanuginosus, Lehm. 



One out of a number of lateral branches arising low down on the stem beneath the 

 level of the soil was afforded me for investigation. The plant, for the branch had become 

 independent by developing a thick adventitious root simulating very closely both in 

 position and structure a primary tap-root, has about the same thickness of stem as the 

 last species described. 



The lower part of the stem, which has a very much less diameter than the major 

 portion, shows, as regards development of vascular tissue, a very great advance on 



