A Third Contribution to our Knowledge of the Anatomy 
of the Cone and Fertile Stem of Equisetum. 
BY 
ISABEL M. P. BROWNE. 
With Plates VIII and IX and seven Figures in the Text, 
I. Material. 
HE present investigations were confined to the cone and the region 
JL transitional between the latter and the fertile stem in Equisetum 
hyemale (L.) and E. giganteum (L.), both species placed by Milde in his 
genus Hippochaete or Equiseta crypt op or a . 
Serial sections were prepared of four cones of E. hyemale. Cones A, B, 
and C were cut into transverse and Cone D into longitudinal sections. 
Cones A, B, and C were young, and though the vascular system was fully 
developed, the internodes would presumably have elongated considerably 
later on. Thus Cones A and C, measured from the insertion of the annulus 
to the base of the apical prolongation of the cone, were 6-5 mm. and 
Cone B 6-9 mm. in length. At its widest point the stele of Cone A attained 
a diameter of 1*5 mm.; that of Cone B one of 1*25 mm., and that of ConeC 
one of 1-3 mm. Cone D was more fully grown; it had attained the height 
of 11 mm. and its stele was i-8 mm. in diameter at its widest point. 
Presumably Cone A would later have attained to very much the same size 
as Cone D. In both the lowest whorl consisted of seventeen sporangio- 
phores. Cones A and D consisted of eleven and ten whorls respectively. 
Cones B and C were on a slightly smaller scale, the former having nine, the 
latter eight whorls, while in both the lowest whorl consisted of thirteen 
sporangiophores. 
Duval-Jouve (p. 221) states that the cones of E. hyemale are 10—12 mm. 
long, and consist of 8-10 whorls. These figures agree fairly well with 
those given above, though two of my cones had eleven whorls. But his 
further statement that the whorls consist of 7-8 members does not hold 
good for the four specimens studied by me. The cones now under con- 
sideration may have been unusually large. Plowever, in the cone of 
E. hyemale figured by Vaucher, the middle whorls, borne on the widest part 
[Annals of Botany, Vol.XXXIV. No. CXXXIV. April, 1920.] 
