444 Browne . — A Fourth Contribution to our Knowledge of 
vestigial annular node ; its protoxylem is also unbranched. Anastomoses 
occur between the twelve other strands, and when the bundles are reconsti- 
tuted they alternate with those below the level of the anastomoses. In the 
cases of the two strands abutting on the two persistent meshes the alterna- 
tion is of the type I have called irregular (Browne ( 1 ), pp. 681-2) ; but the 
phenomenon is very distinct. The protoxylem of the branched strands also 
shows indications of forking (cf. PI. XXI, Fig. 2). In the cases of the first, 
fourth, fifth, sixth, seventh, tenth, and thirteenth strands of the diagram 
(Text-fig. 2) one of the forks of the protoxylem dies out without effecting a 
junction with a neighbouring fork. In the cases of the first, fourth, fifth, 
sixth, tenth, and thirteenth strands the very short forks of protoxylem that 
die out cannot be clearly shown in the reconstruction, owing to the small scale 
of the diagram ; but in all these cases there is a perfectly distinct, short, 
divergent tooth of protoxylem. Both forks of the protoxylem of the third 
strand of the diagram and a fork of the second, seventh, tenth, twelfth, and 
thirteenth strands fuse with the forks of neighbouring protoxylem strands. 
It seems natural to regard the cases in which a fork of the protoxylem dies 
out without effecting a junction with a neighbouring fork as due to reduc- 
tion, the reduction being greater or less according to the length attained by 
the fork before dying out. 
In Cone A of E. sylvaticum three short branches of protoxylem (each 
one of a pair of which the other member persists) end blindly in the meta- 
xylem above the insertion of the annulus. These short branches range from 
150 to 400 [x in length. Since they die out in the metaxylem they are 
presumably unconnected with the increase in number of the sporangio- 
phores (and consequently of the strands of protoxylem) over the leaves 
of the uppermost node. In these cases the forking of the protoxylem occurs 
a little way (about 400-600 f) above the insertion of the annulus, and the 
forks die out at about the level of and to one side of a neighbouring supra- 
annular parenchymatous mesh, formed by the branching of a strand. 
As regards the supra-annular anastomoses the five cones, A to E, 
of E. debile show marked differences. In Cone A three of nine paren- 
chymatous meshes are closed somewhat above the insertion of the annulus, 
and one fresh mesh (of the fourth order) arises. In Cone B one fresh mesh 
(of the fifth order) originates above the insertion of the annulus. As seen in 
the diagram (Text-fig. 4) none of the parenchymatous meshes of this cone 
was closed at this level , but from the distribution of the phloem we may con- 
clude that had the cone reached maturity the mesh between the third and 
fourth strands would have been closed by the differentiation of additional 
metaxylem. In Cone C one of five parenchymatous meshes is closed near 
the level of insertion of the annulus. No clear case of the origin of a 
supra-annular mesh is found in this cone. That arising between and 
slightly below the second and third traces of the lowest whorl may equally 
