982 T ho day and Ber ridge. — T he Anatomy and Morphology of 
2. The three bundles entering the axillary ovule branch each into 
three. In some species (E. Torreyana , E. alata , E. fragilis ) the median 
bundle of each trio passes out into the outer covering ; in other species 
(E. distachya) the abaxial trio does not provide any contribution to the 
outer covering, which thus receives only two bundles. A special case is 
afforded by the uniovulate species, E. altissima and E. trifurca , in which 
the two fertile bracts enclose only a single ovule. This receives either four 
or three bundles, which clearly represent the fused vascular systems of the 
two ovules of the biovulate species. 
3. That the single terminal ovule of these species is actually the product 
of the fusion of the two axillary ovules of the biovulate species is clearly 
demonstrated by a long series of intermediate forms in E. altissima ; 
among which occur biovulate cones, each ovule having two coverings, 
biovulate cones with a common outer covering, and uniovulate cones in which 
an abortive nucellus is more or less fused at the apex with a fertile one. 
4. The structure of the outer covering and its method of vascular 
supply do not support the view that it represents the first whorl of leaves of 
an axillary shoot. It is here regarded as an integument. It is more or 
less angled in the various species and is composed, roughly, of an outer 
brown-celled layer and an inner fibrous layer. The vascular bundles 
traverse the angles and are accompanied towards the apex of the ovule by 
strands of fibres ; they terminate in transfusion tissue. The structure of the 
outer integument is thus very similar to that of Gnetufn (middle covering), 
except that there is here no palisade layer and that the angling of the inner 
fibrous layer corresponds to the outer angling of the seed which does not 
occur in Gnetum , but is present in Welwitschia. The comparison formerly 
drawn between Gnetum and Bennettites is thus further emphasized by the 
study of Ephedra. 
5. The inner covering has no vascular supply, the ring of bundles 
entering the ovule terminating near its base. It is free from the nucellus 
for the upper third of the ovule and is prolonged upwards as a micropylar 
tube with a very strongly cuticularized lining. The opening of the 
micropylar tube is closed in the fertilized ovule by a hardened plug of 
mucilage, and the chink between the two integuments is closed by papillae 
which grow out from the epidermis of the outer covering and firmly clasp 
the inner. The fertilized ovule is thus as efficiently protected as in Gnetum 
with its complex mechanism. Both arrangements are, physiologically, 
abortive attempts at Angiospermy. 
6 . The different species of Ephedra exhibit much variation in the 
number of male sporangia. In E. distachya , E. fragilis, E.nebrodensis , &c., 
the sporangiophore is clearly bifid, and each half bears four bilocular 
synangia. In some species such as E. aspera , E. Torreyana , &c., there is no 
clear separation into two halves, and the upper pair of synangia are fused 
