of the Anatomy of the Genus Selaginella , Spr. 189 
By taking serial sections it may be seen that a gradual fusion 
amongst the steles of the erect axis takes place as the creeping 
stem is approached, until there is left finally one central cord 
and four steles (which bear the leaf-traces), regularly arranged 
round it. These latter then fuse, first in two pairs, and finally 
just above the origin of the shoot from the creeping axis, into 
one semicircular stele, with the central stele lying distinct 
in the convexity. Figs. 83 to 89, PL XII, illustrate the 
gradual fusion amongst the steles of the erect shoot as the 
rhizome is approached. 
3. Anatomy of the creeping axis. 
If now the creeping axis be examined a totally different 
arrangement of vascular tissue is disclosed. The creeping 
stem, like the erect unbranched axis, has homophyllous leaves, 
but these are still arranged in four rows. The leaves are 
closely packed and the growing region is very short. If 
a transverse section be made midway between the points 
of origin of any two erect shoots, it will be seen that the 
centre of the section is occupied by a stele whose xylem has 
no protoxylem elements, and which is surrounded by an 
ill-defined lacuna. This stele is enclosed completely by 
another cylindrical stele consisting of pericycle, phloem, and 
a well-marked ring of tracheids, with four protoxylem-areas 
(or three by fusion of two of these) on its outer edge, to which 
the leaf- traces are attached. Just before the erect shoot 
arises, the outer cylindrical stele opens, becoming horse-shoe 
shaped in section, the opening being on that side on which 
the erect shoot originates, and a fusion takes place between 
the central stele and the upper wing of the crescentic outer 
stele. If the entire stelic system of the erect shoot and 
creeping axis be isolated and compared with serial sections, 
it will be found that the crescentic band of the erect shoot 
fuses with the cylindrical stele only, and that the central cord 
of the erect shoot fuses chiefly with the central stele, but is 
connected with the external cylinder as well. Towards the 
growing-point of the creeping axis the outer stele gradually 
becomes narrower, and finally ends in merismatic tissue. So 
