in the Genus Primula . 
309 
( reseau radicifere ), which, both in the perfect and the imperfect 
steles, not infrequently takes the appearance of an outer 
series of normally oriented supernumerary bundles. This 
strange appearance is found wherever the elements of the 
radiciferous network are cut through transversely. The real 
nature of these outer bundles becomes at once evident in 
those sections which pass through the exact point of origin 
of a root ; here it is seen that their position in the pericycle 
is taken up by horizontally running elements evidently con- 
nected with the root-stele, and belonging to the radiciferous 
network (Fig. 1 ; cf. also Van Tieghem, l.c., Fig. 31). 
In four of the specimens of P. japonic a examined, the 
imperfect type of stele alone was present throughout the 
whole length of the stem. In some it was present in 
the regions towards the base of the stem only, while the 
rest of the stem possessed perfect steles. In the remainder, 
although the imperfect form was present throughout the 
greater part of the stem, perfect steles also appeared in 
limited regions variously distributed. 
Neither did any of the plants of P. obtusifolia that I examined 
show a perfect gamostelic structure throughout. In one plant 
the perfect steles did not appear at all ; in the others, they 
were found only in limited regions situated in different parts 
of the stem. 
The only point of difference between the imperfect steles 
found in P. obtusifolia and those in P . japonica is that in the 
former, owing to the strong sclerosis undergone by the cells 
of the central region of the ground-tissue, the endodermis on 
the inner side could not always be identified with certainty, 
although it is distinctly recognizable in young specimens. 
In P. obtusifolia and P. involucrata those parts of the stem 
which are formed at the end of one season’s growth and the 
beginning of the next do not attain more than about one-third 
of the full diameter of the stem, and in these regions the 
number of steles present is always reduced to three, two, 
or even a single one, shaped like a horseshoe. Further, they 
invariably seem to be imperfect, showing a complete absence 
