1920] 



SMITH— BULBILS OF LYCOPODIUM 



433 



that of a root, but much more irregular. Sometimes it is distinctly 

 diarch (fig. 18), more commonly it is horseshoe-shaped, and some- 

 times almost a complete ring, often with a few tracheids in the 

 center (fig. 19). Surrounding the whole xylem area there are one 

 or two irregular layers of cells, probably a pericycle, and outside 

 these an indistinct sheath (this feature is shown only in fig. 16). 

 This irregular arrangement continues until the fifth and sixth 

 pairs of leaf traces are given off and also the second root. Above 

 that the tissues are still meristematic in the ripe bulbil. The 

 bulbil, like the leaves, is well supplied with stomata, and photo- 

 synthesis proceeds actively. The cause of the accumulation of 

 starch in the bulbil proper and not in the base seems to lie in the 

 absence of phloem in the neck of the bulbil. Here the cells are 



Figs. 18, 19. — Cross-sections of bundle above origin of first root; X320 



in the bulbil surround the xvlem 



the 



plates have not been identified. 



detachment 



per is brought about by a disorganization, apparently a gelatini- 

 ion, of the walls of the xylem cells in the neck. 

 When a ripe bulbil is kept on damp soil it soon germinates. 

 :h roots penetrate the soil and branch repeatedly, and from the 



the 



tip of the bulbil a slender stem is put forth. On this stem 

 leaves, although scattered, are from the first arranged spirally. 

 Jones (5) traced the development of the vascular cylinder in the 

 young plants growing from bulbils of L. Selago and L. serratum, 



simple bundle becomes 



diarch, triarch, etc., 

 on L. lucidulum do 



this 



My observations 

 ision. I find, in 



Tones, that the young stem at its attachment with 



