290 Transactions. 



Further developiuent in complexity takes place by the splitting of the 

 groups of protoxylem. In the young plants of this species, although the 

 groups of protoxylem and the bands of phloem are compact and definite 

 in form, yet from the very first a constant tendency towards rearrange- 

 ment of the elements is apparent. The single crescentic group of proto- 

 xylem may split up into two or even three grou23S of single elements 

 separated by single groups of phloem, and then join together again. 

 And in the typical two-group stage the groups may be either compact 

 and small or broad and extended around the periphery. The vascular 

 cylinder in the mature stem (fig. 86) may be best described as stellate, and 

 corresponds more or less closely with that described by Jones (13, p. 23) 

 for L. squarrosum, the chief difference being that in the New Zealand 

 species the groups of protoxylem are much larger and the outer ends of 

 the xylem rows stouter than in the other species. The phloem is in 

 bands or in isolated islands, as also is the xylem. The configuration of 

 the cylinder has a tendency to alter owing to cross-connections taking 

 place, between the xylem Jaands and groups. The phloem consists of 

 sieve tubes surrounded by a well-differentiated phloem parenchyma with 

 abundant cell-contents. The bands of xylem vessels are not accompanied 

 by any small-celled xylem parenchyma. The innermost and the outer- 

 most zones of the cortex consist of cells with more or less thickened walls, 

 but it is only a layer or two of cells at both the extreme outer and inner 

 edges Avhich stain at all noticeably with safranin, and these only at 

 the cell-corners. There is no marked rearrangement of the tissues of the 

 vascular cylinder preparatory to a dichotomy. In one plant an exact 

 trichotomy of the vascular cylinder was obseiwed in the lower part of 

 the stem. In the ultimate branchlets the number of protoxylem groups is 

 reduced to four or three, the xylem being arranged sometimes radially 

 and sometimes in isolated groups. In these branchlets the leaves, which 

 throughout the plant in this species are comparatively large, are arranged 

 in four to six orthostichies. In the fertile regions the sporophylls are 

 always in four orthostichies, and the number of protoxylem groups is 

 normally three. 



L. varium. 



In this species the stem is thick, but it consists almost entirely of 

 thin-walled parenchymatous tissue. A narrow zone, five or six cells in 

 width, immediately surrounding the vascular cylinder, is slightly scleren- 

 chymatous. The central cylinder itself (fig. 87) is much smaller than 

 in the last species. In the older parts of the stem there are seven or 

 eight massive groups of protoxylem, and these are joined across by 

 metaxylem or left isolated in a varying manner. The configuration of 

 the stele thus cannot be definitely described. The groups of protoxylem 

 not uncommonly join together as in the figure, and thus become greatly 

 extended around the periphery of the cylinder. The cells in the centre of 

 the phloem bands are empty, but are no larger than those of the phloem 

 parenchyma which borders them on both sides. The latter have abund- 

 ant cell-contents, as also do the cells in the pericyclic zone. 



L. Drummondii. 



The main stem here consists of a very loose parenchymatous cortex, 

 the narrow innermost zone of which is sclerenchymatous, and a medium- 

 sized vascular cylinder (fig. 88). The metaxylem elements in the latter 

 are arranged in not very compact bands, and sometimes single isolated 



