TRANSACTIONS OF SECTION K. 783 
as well as relatively larger than in the latter species. Well-developed elaters are 
present in both capsules. 
It appears probable that Cyathodium has been derived by adaptation to damp 
and ill-lighted situations from a well-characterised Marchantiaceous form of about 
the same grade of differentiation as Targionta. The modifications of vegetative 
structure can readily be placed in relation to the change of habitat, while those 
of the sporogonium may have been indirectly necessitated by the reduction in 
bulk of the lower storage region of the thallus and especially of the portion 
bearing the archegonia. 
10. On some Peperomia Seedlings. Ly A. W. Hint, JA. 
11. Exhibition of Specimens illustrating (1) the Comparative Constancy 
of Specific Characters of Eucalypts ; (2) the Relation between the Leaf 
Venation and the Oil Constituents. Dy R. T. Baxen, £.L.S. 
These exhibits consisted of a large number of herbarium specimens of eucalypts 
obtained from trees growing in different parts of the world, and demonstrate clearly 
that the varying environments have produced little or no variation of systematic 
characters, such as buds, leaves, fruits, and flowers. ‘There was also exhibited a 
number of photographs, taken from living leaves, which show leaf venation of the 
various groups of eucalypts, the disposition of which indicates an agreement with 
the oil constituents, which latter were also exhibited. 
12. Hxhibition of Fruits of Melocanna, Melocalamus, and Ochlandra. 
By Dr. Orro Srarr. 
13. Observations on Secondary Thickening in Amarantus spinosus. 
By Horace A, Wacer, 4.2.0. 
This species of Amarantus is very common in Natal, being a troublesome 
weed and growing rapidly on any waste ground. It seems to be able to stand 
the variations of climate better than a large number of plants; and plants in 
Natal have to accustom themselves to extremely irregular conditions of heat and 
moisture during the growing season. 
In its mode of secondary thickening it corresponds generally to the type 
described by De Bary (‘Comp. Anat.,’ &c., p. 590). The centre of the young 
stem is occupied by a number of scattered bundles in a succulent ground tissue. 
On the outside of these bundles is the meristem ring, from which new bundles are 
formed on the inside. In the older part of the stem the intermediate cells given 
off from the meristem ring become thickened and form a fibrous mechanical tissue, 
which becomes more strongly pronounced near the base of the plant. In the 
thickest stems of 5 centimétres diameter this strengthening ring is never more 
than 5 to 8 millimétres thick, but the stem is very strong and sturdy, The leaf 
trace bundles pass into the stem and immediately anastomose with those already 
in the centre of the stem, and only run for a short distance alone, A trans- 
verse section through a node shows a good deal of confusion, due to the anasto- 
mosing of the stem-bundles among themselves and also with the leaf and 
axillary traces. 
In the lower part of the stem the bundles are more numerous in the mechanical 
ring, and do not increase in size so much as those in the central tissue. 
The elements of the xylem are of the usual kind. The phloem is well marked, 
and contains fairly long sieve tubes with slightly oblique sieve plates. In most 
cases well-developed callus can be quite easily made out. This development of 
callus is surprisingly large in a plant which is an annual and only lives for a few 
