1907-8.] Morphology of the Cone of Lycopodium cernuum. 357 
12 mm. and a diameter of 3 mm. Their general external appearance is repre- 
sented in the figure given by Pritzel in Die natiirlichen Pflanzenfamilien * 
in which the abrupt transition from the vegetative leaves on the branchlets 
bearing the cones to the sporophylls is shown. The sporophylls, like the 
vegetative leaves, are borne in alternating whorls of five, and thus form ten 
vertical ranks on the axis of the cone. Each sporophyll consists of a 
horizontal base and a nearly erect lamina with a fimbriate margin. The 
large sporangium is attached by a relatively small area of insertion or stalk 
close to the distal limit of the horizontal sporophy 11-base, and lies against 
the upper surface of the latter. The lower portion of the sporophyll-base 
is occupied by a large mucilage cavity. The mutual relations of the sporo- 
phylls in the cone are more complicated than appears from any of the 
accounts hitherto given. This will be evident from a study and recom- 
bination of figs. 1-4, which represent radial longitudinal, tangential, and 
transverse sections of mature cones; these figures are outlines, based on 
camera lucida drawings, and not diagrammatic. 
The radial section (fig. 1) passes on either side through a vertical series 
of sporophylls, the two series belonging of necessity to alternate whorls. 
In the case of one sporophyll on the left, which has been cut in an absolutely 
median plane, the course of the slender vascular trace can be followed from 
the stele into the lamina. The leaf -trace originates from the stele at the 
level of the insertion of the whorl of sporophylls below, or, what comes to 
the same thing, at the lower limit of the base of the sporophyll which it 
supplies. Structures standing at the same horizontal level in the alternat- 
ing whorls can be readily ascertained by a comparison of the two sides of 
this section. 
Each sporophyll shows in section the thick horizontal base and the 
obliquely erect lamina already referred to. The lower portion of the sporo- 
phyll-base is occupied by a large mucilage cavity (m). The mucilaginous 
change extends to the surface involving the epidermis, so that this 
portion of the sporophyll-base may be described as consisting of a mass of 
mucilage bounded below by a structureless membrane.]- The upper portion 
of the sporophyll-base consists of persistent tissue, traversed by the vascular 
bundle; and the outer (abaxial) surface of the sporophyll-base is also 
composed of persistent tissue. The lamina has no mucilage cavity and is 
continuous with the persistent tissue of the base. The vascular bundle 
traverses the pedicel-like portion of the base and continues throughout 
* Theil i., Abth. iv., p. 603, fig. 379. 
t The extension of the mucilaginous change to the surface is shown in PI. xix., fig. 1 3, 
of Mr T. G. Hill’s paper in the Annals of Botany, vol. xx., but is not commented on. 
