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aggregation of several protophylls. This takes place either close to the 

 growing end of the rhizome or at some point farther away from it, 

 although the position of the young stem is always nearer to the growing 

 end than to the first-formed protocorm proper (figs. 66-69, 71, 73, 75-78). 

 Almost immediately vascular tissues are initiated from the stem-apex, 

 and extend down into the upper region of the rhizome, receiving on the 

 way strands from the neighbouring protophylls (fig. 71). In the rhizome 

 these vascular tissues bend round at an angle which is more or less sharp 

 according to whether the stem-apex is farther away from the growing- 

 point of the rhizome (fig. 71) or close to it (fig. 73), and take a course 

 thiough the tissues of the rhizome, near to its dorsal surface, towards its 

 growing end. At a later stage this vascular strand is surrounded by a 

 slight zone of sclerenchyma (Plate XVII, fig. 1). The arrangement of "the 



Fig. 74. — Lycopodium laterale. Portion of rhizome shown in fig. 73, 

 showing relation of vascular strand to the apex of root. X -25. 



elements in the strand is described in the next section of this paper. 

 Fig. 72 is a highly magnified drawing of a poi'tion of fig. 71, and shows 

 that the vascular strand of the stem and first root as it passes through 

 the body of the rhizome is developed from the actual tissues of the 

 rhizome. T\% same fact is also apparent from fig. 74, which is a magni- 

 fied drawing of a portion of fig. 73, and from Plate XVII, figs. 1 and 2. 

 At the same time that the vascular strand from the stem-apex is taking 

 form along the body of the rhizome in the direction of its growing end, 

 the latter at a point on the surface towards the dorsal side begins 

 to grow outwards and downwards to form a finger-like protuberance 

 (figs. 68, 69, 73, 74). Into this protuberance the vascular strand passes. 

 This is the first root. The extension in length of the rhizome is brought 

 to a close by its initiation. All subsequently formed roots in the young 

 plant emerge adventitiously from the stem, and do not pass through the 



