62 



BOTANICAL GAZETTE 



[JANUARY 





It would be dangerous to draw any serious conclusions from a 

 study of 2 or 3 sporelings, all of which had reached the leafy stage; 

 but, in the present condition of the subject, it seems worth while 

 to describe a few features. The study was made from the sporelings 

 shown in figs. 9-1 1. 



In L. volubile the foot is quite small, and although somewhat 

 larger in L. scariosum y no vascular strand extends into it, but a few 

 cells, not lignified, point in its direction. The vascular strand 

 extends in an unbroken line from the tip of the stem to the tip of 

 the root, which in both species is late in appearing. 



The sporeling of L. volubile shown in fig. 9, and that of L. 

 scariosum shown in fig. 10, were sectioned transversely down to 

 the crown of the prothallium, and the portion below the crown was 

 then cut longitudinally. It would have been much better if trans- 

 verse sections had been continued throughout. In both species 

 the leaves are surprisingly like the protophylls of L. later ale. 

 Throughout a considerable portion of their length the transverse 

 section is circular, and even in the broader middle region the leaves 

 are thick and spongy, consisting almost entirely of very loose 

 parenchyma with large intercellular spaces and a single vascular 

 strand. Stoma ta are irregularly scattered over the entire surface 

 (fig. 16). The adult leaves in both species are rather thin. 



In L. scariosum the shifting topography of the stele is a conspicu- 

 ous feature, especially in the upper, leafy region ; in the lower half 

 of the sporeling, where there are only a few scale leaves with no 

 leaf traces, the arrangement is more uniform. Near the middle of 

 the leafy portion, a hexarch, pentarch, and tetrarch condition occurs 

 within a vertical distance of 1 mm. Throughout the lower one- 

 third of this specimen the stele is rather constantly tetrarch; but, 

 just above the foot a few sections show a triarch and even a diarch 

 stele. That the leaf traces connect with the protoxylem points 

 is evident at a glance; but whether the leaf traces determine the 

 topography is not so clear. However, it is significant that the 

 stele is more complex in the leafy region and that it attains its 

 greatest complexity in mature plants with larger leaves and vigorous 

 leaf traces. In various places there are indications of the banded 

 arrangement characteristic of the adult stele. 



