446 Browne . — Fourth Contribution to our Knowledge of 
contrary, in Cone A a complex of three strands gives rise to two traces, 
while two more traces depart from a single strand ; and in Cone C three 
traces depart from a complex of two strands, while another complex of 
two strands gives off but a single trace. Consequently, in these two cones 
(though not in Cone B) the traces of about half the sporangiophores of the 
lowest whorl are anatomically superposed, though somewhat irregularly so, 
to the corresponding leaf-traces of the last vegetative whorl. At the base 
of Cone D this superposition of the spor- 
angiophore-traces to leaf-traces was also 
noticeable (cf. Text-fig. 1 1 ). It is possible 
to see in this condition the last indication 
of the existence in the ancestors of E. 
variegatum of anastomoses marking the 
former presence of a node, now obsolete, 
at the insertion of the annulus. Such an 
interpretation is admittedly very doubt- 
ful, and were it not for the numerous 
anastomoses found in other species in 
the neighbourhood of the insertion of the 
annulus — anastomoses that lead to an irregular superposition of some of the 
traces of the sporangiophores to certain of the leaf-traces— and for other 
indications of an obsolete or obsolescent node at this level, the point would 
not have been mentioned at all. 
VII. General Considerations. 
Barratt, in a recent paper, has formulated certain generalizations 
concerning the cone and annulus of Equisetum which seem to me to rest 
upon an insecure foundation. While refraining from discussing the morpho- 
logical nature of the sporangiophore, which is too wide a question to 
be conveniently treated in this paper, I shall, therefore, quote and comment 
upon some passages from her paper. But before doing this I wish to 
acknowledge the inadequacy of the description of the xylem of the cone 
given in my paper on Equisetum arvense (Browne (1), p. 666) and 
quoted in part by Barratt. The quotation as given by Barratt runs as 
follows: ‘She 1 states (1, p. 666), “In a good many places there are 
internally to the bands or ring 2 isolated tracheides or little groups of 
tracheides, usually of small size. . . . Such tracheides or groups of tracheides 
do not as a rule persist for any considerable distance in a vertical direction ; 
in the internode they occur also internally to the separate strands of xylem.” 5 
Barratt adds : ‘It may be stated quite definitely that these elements 
belong to the protoxylem, although Browne does not apparently identify 
Text-fig. ii. Reconstruction of 
stele of Cone D of E. variegatum from 
below insertion of annulus to a point above 
level of first whorl of sporangiophores. 
Axial xylem black ; traces and parenchyma 
white, x 20. 
1 i. e. the present writer. 
2 i. e. of xylem. 
