I IOI 
Relationships of the Gnetales . 
Evidence from other sources supports this view. Hill and de Fraine , 1 
from their study of the vascular system of the seedlings, conclude that in 
this respect Ephedra strongly resembles Araucaria and the Podocarps. 
Miss Sykes states that the transition phenomena between root and stem in 
W elwitschia strongly resembles that in Araucaria . 
If the anatomical evidence leads to these conclusions the gametophytic 
evidence is just as conclusive. According to Land’s 2 description the male 
gametophyte is typically Coniferous in all details. The female gametophyte 
differs from that of Coniferales only in the long neck of the archegonium 
and presence of a pollen-chamber, features which he explains on a physio- 
logical basis. 
Thus all the essential features, both gametophytic and anatomical, 
indicate some relationship to the Conifers. Opposed to these and in favour 
of the Cycadalean affinity we have so far only the evidence of floral 
organization. 
With regard to the Angiospermous relationship Ephedra presents 
several points of interest. Prominent among these is, of course, the pos- 
session of vessels. But, as has been pointed out, the vessels of Ephedra 
exhibit vital differences from those of the Angiosperms, although the rare 
occurrence of fusion of perforations lessens this difficulty. An equally 
striking feature and one which has been overlooked is the possession of 
broad rays like those of the lower Dicotyledonous woods, and especially 
their origin by compounding. This is really a feature of first importance. 
Among those of lesser value one should recall the separation of the leaf- 
traces on the stem and the presence of an absciss periderm in the leaf. 
Summary. 
The pith presents two striking features in the presence of a peridermal 
diaphragm at the base of each internode and occasional patches of lignified 
cells simulating centripetal wood. 
The primary vascular bundles run regularly through one internode and 
lose themselves in a nodal girdle of tracheides. Throughout the internode 
their structure is endarch, but at the node occasional elements like trans- 
fusion tracheides are present in a centripetal direction. Transfusion tracheides 
also occur laterally to the bundles in the internodes of some species. 
The leaf-traces are double and the two strands are inserted separately, 
usually with a vascular bundle between. In structure they are endarch 
throughout. 
The tracheides of the secondary wood are characterized by the arrange- 
ment of the pits in both the Abietinean and Araucarinean fashion, structure 
1 On the Seedling Structure of Gymnosperms, IV. Gnetales. Ann. Bot., 1910. 
2 Spermatogenesis and Oogenesis in Ethedra trifurca. Bot. Gaz., 1904. 
