664 Browne . — Contributions to our Knowledge of the 
tion of the Equisetaceous bundle ; in 1902 a general account of the 
Equisetaceae was given by Sadebeck in Engler and Prantl’s ‘ Naturliche 
Pflanzenfamilien 5 ; the same year appeared Chauveaud’s account of the 
anatomy of the root, while the next year the origin and affinities of the 
Equisetaceae were discussed by Lignier. In 1905 the affinities of the genus 
were considered by Campbell, and in 1906 Sykes recorded peculiar nodal 
tracheides in a specimen of E. maximum. In 1907 appeared Queva’s 
important paper on the stem and leaf of Equisetum and also a short note 
on the sporangium by Hawkins, while next year was published a second 
edition of Campbell’s ‘Mosses and F'erns’. The year 1908 also witnessed 
the publication of Bower’s ‘ Origin of a Land Flora in which Equisetum 
is treated at some length, and of Halle’s account of the Mesozoic Equi- 
setaceae of Sweden. In the next year Eames published a paper dealing 
with the anatomy of Equisetum , and Jeffrey discussed this subject in 
a paper entitled ‘ Are there foliar gaps in the Lycopsida ? ’ In this year, 
1909, there also appeared a short account of fossil Equisetaceae by Fritel 
and Viguier, and a note by Stiles on the anatomy of a branched cone 
of Equisetum maximum. In 1911 Ludwigs published an account, largely 
biological, of the genus, while in 1912 Vidal dealt with the segmentation 
of the apical cell and the early stages of anatomical differentiation in 
E. palustre. 
Material. 
The present investigations were confined to the cone and the upper 
part of the fertile stem in three British species of Equisetum : E. arvense , 
E. palustre , and E. limosum . In the case of the first species two complete 
cones, henceforward termed A and B respectively, were cut into continuous 
series of transverse sections. Cone A was very young ; it was dug up in 
October and would, therefore, have remained another five months under- 
ground. Nevertheless, the xylem of the cone was almost completely 
differentiated ; this series of sections extended downwards below the cone 
and included four of the vegetative nodes. Cone B was more or less mature, 
and the series of sections below it only extended to beneath the annulus. 
Of a larger cone, C, serial transverse sections were made from below the 
annulus through the lowest seven whorls of sporangiophores. To confirm 
the phenomena observed in Cones A and B the upper parts of two cones, 
D and E, were cut serially ; the latter cone, though otherwise normal, had 
two annuli ; satisfactory series through this region of the cone could not, 
however, be obtained. Another cone, F, also had two annuli, and of this 
specimen a continuous series of sections extending from below the lower 
annulus through the three basal whorls of the cone was prepared. The 
transitional region from below the annulus through the basal whorl of the 
cone was also studied in two cones ; in a very large one, G, the diameter of 
