Igto] SAXTON—EMBRYO OF ENCEPHALARTOS he 
In the last stage of intraseminal development the primordia of 
one or two plumular leaves reach a moderate size. ‘The cotyledons in 
the mature embryo are fused throughout their whole length, by both 
margins at the base, and by either one or both margins near the apex. 
Fig. 16 represents a transverse section in which they were fused by 
one margin only; the part of the section marked x is drawn in detail 
in fig.17. This shows the very intimate union of the epidermal cells 
and their collenchymatous thickenings. 
Fig. 18 represents the root and stem apices, the bases of the 
cotyledons, and the first plumular leaf. The root meristem has now 
increased considerably in size, but has not otherwise changed its 
character in any way, so that what is physiologically the root cap is 
only the distal end of the suspensor as morphologically equivalent 
to part of the root cap of any ordinary angiospermous embryo. The 
embryonal tubes in certain conifers are evidently equivalent to the 
Whole suspensor of Encephalartos. 
From the preceding account it is clear that there is a very close 
resemblance between the embryogeny of Encephalartos and that of 
Ginkgo as described by Lyon (1. c.). 
Summary 
1. The suspensor is developed by the division and elongation of a 
8toup of cells at the proximal end of the embryo. 
2. This group of cells forms later the root meristem. 
__ 3- Branching of the suspensor has been observed once, resulting 
in the formation of two approximately equal embryos. 
4. The cotyledons are initiated by the more rapid growth of two 
Stoups of cells of the apical meristem. 
5- The canals appear before the differentiation of plumular leaves, 
and probably contain both tannin and mucilage, being formed 
lysigenously. 
- Avery intimate connection is established between the epidermal 
cells of fusing cotyledons. 
7. The suspensor is morphologically a root cap. 
8. The embryogeny of Encephalartos is very similar to that of 
Gingko. 
SoutH AFRICAN COLLEGE 
Cart Town 
