410 
THE GARDENING WORLD 
February 23, 189S. 
THE CORAL ANIMALS. 
In his discourse at the Royal Institution on Tuesday 
afternoon, Professor Charles Stewart described some 
of the vast family of coral animals and the means 
by which these creatures build up the strange rocky 
skeletons upon which they are found growing in the 
depths of the salt water. It need hardly be 
explained that the pretty red “coral’' used for 
bracelets is the product of only one particular species 
of coral animal. There are hundreds of different types 
of coral “ polyps,’’ and they produce the widest 
variety of form and structure in the skeletons they 
leave behind. The most familiar “ corals ” are 
elaborate skeletons of white or whitish-grey lime¬ 
stone, something like petrified sponges. Many of 
these are of great beauty, but it is the beauty of 
form and not of colour. The activity and energy 
with which the coral colonies elaborate their lime¬ 
stone houses is best appreciated by considering the 
share they have taken in building up the great coral 
reefs that form so important a part of the earth’s 
crust. For countless ages these industrious animals 
have been at work in the blue waters of the ocean, 
ceaselessly piling up reefs and rocks and islands, and 
they are carrying on the work just as energetically 
to-day as ever. The mariner finds this to his cost 
when some unmarked reef that has been growing 
unperceived tears the bottom out of his ship in the 
Pacific. 
But this process of building up a grotto to grow in 
is a highly complex business. The lime is deposited 
by the surface cells of the “ectoderm,” or outer 
lining of the polyp, and as the walls of the building 
grow and envelop the base of the builder’s body, 
that base accommodates itself to the shape of the 
rockwork it is sitting upon. In most cases the 
growing stonework seems as if pushed up like a 
series of plates set on edge into the jelly-like body of 
the animal. Meantime the walls are growing all 
round and forming a cavity into which the creature 
can retreat if danger threatens. But we must still 
remember that this only describes the course of 
events with regard to one particular individual 
owning a mouth and tentacles, whereas there are 
millions of such individuals all growing more or 
less joined together, and forming a great colony of 
compound sea anemone which covers the coral rock 
beneath as with a mass of living, prey-capturing, 
feeding, stinging, budding, growing jelly. Add to 
this conception that the limestone skeleton under¬ 
neath is growing together with equal complexity at 
the same time, and some idea may be obtained of 
the life-processes going on in a coral reef. The 
actual result of such a fine confused business is 
generally a continuous animal structure which grows 
on the whole in certain definite ways, according to 
its character and species. 
Coral, from the scientific point of view, consists 
not only of these myriad-chambered mansions of 
limestone, but of the inhabitants that dwell in them. 
Both the dwellings and the dwellers are very com¬ 
plex in their structure, and to storm the stronghold 
of their complexity we must approach by degrees. 
Last week the professor described some of the hydra 
and medusa families—comparatively simple struc¬ 
tures [of living jelly that catch their prey by long 
fingers arranged round their mouths. The coral 
animal is a similar creature, but is more closely 
related to the sea anemones. A sea anemone, in 
fact, is a large coral animal which does not build a 
stoney mansion to dwell in, but prefers to remain an 
apparently unprotected lump of jelly sticking to the 
surface of the rock. As every seaside visitor knows, 
it is something in shape like an inverted pot hat with 
fringe of petals round the rim. The “ petals” are 
really fingers armed with cruel stings, by means of 
which prey is captured and thrust into the mouth, 
whence it passes into the recesses of the " hat ” for 
digestion. Inside the hat is stiffened by a number of 
ribs of jelly (called the sarco-septa) radiated outwards 
to the walls. Like most of the polyp family, these 
creatures throw out “ buds,” and split up and 
exhibit a variety of forms of growth, besides having 
a true sexual method of reproduction. Now if we 
can picture somewhat minute animals of this sort 
which have a habit of depositing particles of lime 
under their base so that they build up around them 
a sort of grotto to dwell in, we arrive at a rough con¬ 
ception of the coral animal. 
But it may be objected, if the limestone skeleton 
is thus continually being added to the individual 
polyps must soon be buried in pits of their own 
digging. And this is precisely what would happen 
if the polyp, when it gets uncomfortably deep down, 
did not draw itself out of the cell and start to build 
a new floor across higher up. In this way we find 
the coral structure consisting of myriads of tubular 
galleries divided up at intervals by cross partitions, 
each cavity representing an old dwelling-place dis¬ 
carded by its former tenant. The shapes and ramifi¬ 
cations of these galleries vary, of course, with the 
kind of coral constructing them. Professor Stewart 
had on view many striking types of these calcareous 
coral growths, some of great beauty, others of 
curious form. In one case the skeleton grew as a 
stony plate, with the polyps all on one jside, and it 
was pointed out that wherever the plate was folded 
and brought together, it was two dead sides that 
approached each other, and not the living faces. In 
the millepore corals the galleries and the polyps in¬ 
habiting them are almost microscopic in size. Here, 
however, the polyps are widely different from the 
sea anemone type, being practieally branching 
“ hydrae,” like those described last week. But all 
the coral animals possess the peculiar weapons of 
offence of the polyp family, namely, the poisonous 
stinging organs, which render the race terrible to the 
finny tribes of the deep .—Daily Chronicle. 
-- 
ORNAMENTAL SPECIES 
OF PHYLLANTHUS. 
Few genera of so vast extent as Phyllanthus are so 
poorly represented in gardens, yet a number of 
exceptional interest and ornament are more or less 
widely cultivated and cherished by those who under¬ 
stand their merits and know how to utilise them to 
the best purpose. Some 450 species are known to 
science, and so varied are they in the structure of 
their leaves, stems, and branches that botanists have 
described them under forty-eight genera. Natural 
affinity is now, however, better understood, and not¬ 
withstanding the dissimilarity prevailing amongst 
them in general characters the structure of the 
flowers and fruits is closely identical in all. The 
differences in the foliage and branches are due chiefly 
to the physical conditions surrounding them in their 
native habitats consequent upon geographical range. 
Most of them require stove treatment, particularly 
during the colder period of the year, and as the 
foliage and its substitutes constitute their most 
important and ornamental character, they may 
simply be treated like other fine foliaged plants and 
used for similar purposes. As a rule they are not 
particular in the matter of soil, but a mixture of 
good fibrous loam, peat, and some charcoal about 
the size of marbles, with sufficient sand to render 
the whole porous and open, will constitute a suitable 
compost for the most of them. Small plants are in 
the majority of cases best suited to the requirements 
of private establishments, and a stock can easily be 
maintained by propagation from cuttings. The 
latter should consist of shoots that have completed 
their growth and become matured, and should be 
firmly inserted in sandy soil in pots and placed in a 
propagating frame. 
Phyllanthus speciosus. —This is at once the 
neatest and the most ornamental of a group best 
known in gardens under the name of Xylophylla, 
which means woody leaves, in allusion to the flattened 
branchlets usually regarded as leaves by those 
unacquainted with structural botany. This illusion 
is still further heightened by the fact that the 
lanceolate, dark green branchlets are arranged in 
two ranks or rows upon the branches which thus 
simulate compound leaves, arranged in a sort of 
loose crown around the ends of the leading stems. 
Young plants confined to a single stem are the most 
ornamental, and in that condition may be usefully 
employed to furnish variety amongst the plants, that 
however excellent in themselves, lose somewhat in 
interest by their exceeding commonness. The species 
was introduced from Jamaica in 1818. 
P. angustifolius. —Notwithstanding the fact 
that this species belongs to the same sectional group 
as the above, its general habit is considerably 
different. The leaf-like, flattened branchlets are 
dark green and lanceolate or linear lanceolate, greatly 
elongated, and assume a sharply ascending direction. 
For the latter reason the species appears to best 
advantage when allowed to grow into a bush of 
some size. It is a native of the West Indies, from 
whence it was introduced to this country in 1789. 
Specimens may occasionally be seen in gardens 
under the name of Xylophylla elongata and X. mon- 
tana, though the latter is by some considered a 
distinct species. 
P. epiphyllanthus. —This was brought from 
Cuba in 1699, and forms a dwarf branching shrub, 
with narrowly, sickle-shaped branchlets about 4 in. 
to 5 in. long. The small, brownish-red flowers are 
borne in clusters from the notches all along the 
edges of the flattened branchlets, as in the two pre¬ 
vious cases, and should dispel the notion that they 
are leaves. It is also known as P. falcatus. 
P. glauscescens. —Totally unlike either of the 
above in general aspect, this is, perhaps, the most 
popular of the genus in cultivation. Its dwarf 
habit and neatness in every respect entitle it the 
proud position it holds. From the short, upright 
stems, slender branches are given off horizontally, 
and bear two rows of ovate and real leaves, but their 
arrangement on the slender shoots gives the latter 
the appearance of compound leaves. To add to this 
graceful character, the clusters of brownish-red 
flowers hang down beneath the horizontal branches 
with their leaves, and present an appearance of so 
many miniature tassels dangling beneath the same. 
In most species the flowers are so small and incon¬ 
spicuous as to attract no attention whatever, and 
herein lies the exceptional merit of P, glaucescens, 
a Mexican plant, that well deserves a place in every 
collection of plants. It usual height is 12 in. to 
15 in. 
P. nivosus. —The foliage is here again the most 
ornamental part of the plant, but for a different 
reason. The leaves are ovate, and in their arrange¬ 
ment of an ordinary character, but they are varie¬ 
gated, splashed, mottled and lined with white, so 
that in well-coloured specimens we have a highly 
ornamental plant indeed. Neatly-grown and bushy 
specimens 18 in. to 2 ft. in height are well worthy of 
a place in any well-kept and well-cared for stove or 
warm conservatory. The specific name refers to this 
variegation, which has a snowy effect against the 
dark green of the rest of the leaves. It is a native 
of the Islands of the Pacific, from whence it was 
introduced in 1873. A high temperature and a 
moist atmosphere suits it well, but on the whole it 
is a very tractable subject. 
P. Chantrieri. —In habit this may be compared 
to P. speciosus, but is altogether larger in all its 
parts and possesses true leaves. The stems are 
upright, stout, and in plants of a useful size are 
solitary; from these long, horizontal or drooping 
branchlets are given off, each bearing two rows of 
lanceolate-elliptic leaves. Owing to the length of 
these shoots, the plant has the appearance of a 
single stem furnished with a handsome crown of 
pinnate leaves. Small plants are both useful and 
ornamental. 
P. juglandifolius. —As the specific name implies 
this species bears no small resemblance to a Walnut 
tree. The stems are stout and the lateral branchlets 
bear relatively large ovate leaves in two ranks. The 
plant has the same general appearance as P. 
Chantrieri, but in every part is on a much larger 
scale, and attains a considerable height, so that to 
be seen in its best character it requires a tall roofed 
conservatory or one in which there is ample room 
for development. The correct name of it is con¬ 
sidered to be P. grandifolius, and it comes from 
South America. 
--*»- 
HEDGE PLANTS. 
For a long time past those who have had to make 
new hedges have invariably chosen the White-thorn 
(Hawthorn) for that purpose. In well cultivated 
fertile soils, and in suitable situations as regards 
climate, fine hedges of White-thorn may be raised if 
attentively cared for and regularly trimmed. But 
there are many conditions of soil and climate which 
make it impossible to obtain good White-thorn 
hedges even if the experiment be tried without 
regard to cost. Neither in a dry soil, in a gray sand, 
in gravel, or in heath land, nor yet in bog land, cold 
flat land, or on steep, sun-burnt slopes, can a good 
hedge of White-thorn be accomplished, much less in 
exposed northern regions where the continued dura¬ 
tion of cold for long periods is a bar to the progress 
of vegetation. Hence it is that we see so many 
failures when attempts are made to make use of the 
White-thorn. Yet it is the desire of every assiduous 
proprietor to see his estate well fenced in. 
In Sweden the upright growing Box-thorn is a 
tougher and much more reliable plant, as even in 
