Anatomy of the Cone and Fertile Stem of Equisetum. 247 
one in which any of the traces of the sporangiophores are markedly reflexed, 
and it is the species in which we get the greatest elongation of the nodes 
and reflection of the sporangiophores. 
Thus in the lowest whorls of Cones A and C of E. arvense we get an 
average downward divergence of the traces of 161 y and 157*5 1 1 respectively. 
In Cones A and B of E. palustre the traces of the lowest whorl have an 
average downward divergence of 28 ju, and 22*75 /x respectively ; in Cone C of 
this species, var. polystachion , which was younger, all the traces pass out 
horizontally or obliquely upwards, while in Cones A, B, and C of E. limosum , 
all young cones, the average divergence of the traces, even of the lowest 
whorls, is upwards. In the cones of all these species, except Cone C of 
E. arvense (which is older and larger than Cone A of this species), the 
traces of the second whorls passed out horizontally or with an average 
upward divergence. In Cone C of E. arvense the average divergence of 
the traces of the second whorl was a downward one of 14*09 /a (for details 
as to the age and size of these cones the reader is referred to my earlier 
paper). 
These figures are significant. Yet, though the descending course of 
certain traces seems to be chiefly due to the pull exerted by reflexed 
sporangiophores and to the greater elongation of the stele than of the 
outer tissues of the stem, it is possible that a slightly downward course 
of the traces of the lowest whorls, even at their origin, is a characteristic of 
the cones of E. maximum , for I was unable to obtain a cone young enough 
to be sure that a very slight downward curve of the traces of the lowest 
whorl did not exist at the moment of lignification of the tracheides of the 
trace. 
Abnormal Behaviour of some of the Traces in the First 
and Twelfth Whorls of Cone A. 
In the longitudinal reconstruction of the axial xylem of Cone A Plate XII 
may be seen four white crosses, three in the lowest and one in the twelfth 
whorl. These are to be found on strands opposite which, at that level, 
incoming traces died out in the cortex. Of the three abortive traces of the 
lowest whorl two occur in the neighbourhood of the sixth and seventh traces 
of the longitudinal reconstruction. These two additional traces penetrate into 
the cortex of the stem from the two unusually large sporangiophores 
supplied by the sixth and seventh traces respectively. Within the 
sporangiophores they are of quite normal development; indeed, the abor¬ 
tive trace lying near the seventh trace is, throughout its course, rather 
larger than the latter. Further, the large sporangiophore supplied by the 
fifth trace possesses another well-developed trace not marked in the recon¬ 
struction, as it dies out at the point of junction of sporangiophore and axis. 
In the third case an abnormal trace between the twenty-first and first traces 
