Comparative Anatomy of the Casuarineae . 257 
A similar case has been described in that part of the paper 
dealing with Casuarina. 
Structure of the Seedling. 
The seedlings of Ephedra , Gnetnm , and Casuarina show 
great similarity of structure. The seedling has two cotyle- 
dons, the number varying in the two latter genera sometimes 
to three, as occasionally happens in several Dicotyledons. 
Alternating with the cotyledons, higher up on the stem, 
are two plumular leaves ; these may have branches in their 
axils ; the cotyledons also have branches in their axils ; and 
there are often secondary axillary branches inserted between 
the primary ones and the cotyledons. These points are 
common to all three genera. 
A transverse section through the lowest internode of the 
plumular stem of Casuarina 1 will show eight, or sometimes 
more, central bundles, which have arisen by the splitting 
of each of the four bundles which have passed into the 
centre from the later-formed leaves above. A little lower 
down these eight bundles fuse again in twos, and four central 
bundles as before is the result. This splitting up of the 
central bundles is also described as occurring in the seedling 
of Gnetum 2 . Where the section passes through adherent 
portions of the two first plumular leaves and the two coty- 
ledons, a more complex system of bundles will be shown. 
The bundle of each of the two first leaves will appear some 
way out. Between each of these bundles and the central 
bundles of the plumular stem will be seen two bundles, which 
evidently belong to a branch in the axil of the leaf. Then 
alternating with the position of the leaves, and still farther 
out, will be about four bundles coming from each cotyledon, 
and between these and the central bundles of the stem on 
each side, two large bundles from an axillary branch. Still 
further down, at the median point of insertion of the coty- 
ledons, we see four central bundles as before, the bundle 
1 Morini, Anatomia del Frutto delle Casuarinee, 1890. 
2 Bower, Quarterly Journ. Microsc. Science, 1882, p. 287. 
