Page:EB1911 - Volume 21.djvu/494

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472
PHORONIDEA

branches a very large number of lurid red or yellow, somewhat tubular flowers, recalling those of an aloe, and from 1 to 2 in. long. After lowering the plant dies down, but increases by new lateral growths from the rootstock. The plant will grow in almost any soil, but best on light rich soil, by the side of rivers and brooks, where sheltered from the wind.

Phormium has been treated as a cultivated plant in New Zealand, though only to a limited extent; for the supplies of the raw material dependenoe has been principally placed on the abundance of the wild stocks and on sets planted as hedges and boundaries by the Maoris. Among these people the fibre has always been an article of considerable importance, yielding cloaks, mats, cordage, fishing-lines, &c., its valuable properties having attracted the attention of traders even before colonists settled in the islands. The leaves, for fibre-yielding purposes, come to maturity in about six months, and the habit of the Maoris is to cut them down twice a year, rejecting the outer and leaving the central immature leaves. Phormium is prepared with great care by native methods, only the mature fibres from the under-side of the leaves being taken. These are collected in water, scraped over the edge of a shell to free them from adhering cellular tissue and epidermis, and more than once washed in a running stream, followed by renewed scraping till the desired purity of fibre is attained. This native process is exceedingly wasteful, not more than one-fourth of the leaf-fibre being thereby utilized. But up till 1860 it was only native-prepared phormium that was known in the market, and it was on the material so carefully, but wastefully, selected that the reputation of the fibre was built up. The troubles with the Maoris at that period led the colonists to engage in the industry, and the sudden demand for all available fibres caused soon afterwards by the Civil War in America greatly stimulated their endeavours. Machinery was invented for disintegrating the leaves and freeing the fibre, and at the same time experiments were made with the view of obtaining it by water-retting, and by means of alkaline solutions and other chemical agencies. But the fibre produced by these rapid and economical means was very inferior in quality to the product of Maori handiwork, mainly because weak and undeveloped strands are, by machine preparation, unavoidably intermixed with the perfect fibres, which alone the Maoris select, and so the uniform quality and strength of the material are destroyed. The New Zealand government in 1893 offered a premium of £1750 for a machine which would treat the fibre satisfactorily, and a further £250 for a process of treating the tow; and with a view to creating further interest in the matter a member of a commission of inquiry visited England during 1897. The premium was again issued in 1899. In 1903 it was stated that a German chemist had discovered a method of working and spinning the New Zealand fibre. An idea of the extent of the growth of the fibre may be gathered from the fact that the exports for 1905 amounted to 28,877 bales at a value of nearly £700,000.

Phormium is a cream-coloured fibre with a line silky gloss, capable of being spun and woven into many of the heavier textures for which flax is used, either alone or in combination with flax. It is, however, principally a cordage fibre, and in tensile strength it is second only to manila hemp; but it does not bear well the alternations of wet and dry to which ship-ropes are subject. The fibre has come into use as a suitable material for binder-twine as used in self-binding reaping machines.

PHORONIDEA, a zoological order, containing a single genus Phoronis, which is known to be of practically world-wide distribution, while there are many records of its larva, Actinotrocha, from localities where the adult has not been found. Phoronis is often gregarious, the tubes which it secretes being sometimes intertwined in an inextricable mass. These associations of individuals can hardly be the result of the metamorphosis of a corresponding number of larvae, but are probably due to a spontaneous fragmentation of the adult animals, each such fragment developing into a complete Phoronis (De Selys-Longchamps). The animal is from a quarter of an inch to six inches (P. australis) in length. The free end of the long vermiform body ends in a horseshoe-shaped “lophophore,” or tentacle bearing region (fig. 1, a), which strikingly resembles that of the Phylactolaematous Polyzoa (see Polyzoa).

(After Allman.)

Fig. 1.—The Tentacular End of Phoronis, with most of the tentacles removed.

a The horseshoe-shaped lophohore.
b, Mouth.
c, Optical section of the epistome (seen immediately below the end of the reference-line).
d, Oesophagus.
e, Intestine.
f, Efferent vessel.
g, One of the two efferent lophophoral vessels, uniting to form f.
h, Dorsal or afferent vessel.
i, Body-wall.
k, Fused bases of the tentacles.


(After Benham.)

Fig. 2.—Dorsal View of Phoronis australis, showing the spirally coiled ends of the lophophore.

a, Anus.
D, Posterior surface.
ep, Epistome.
gl, Lophophoral organ.
i.t., Bases of inner tentacles.
m, Position of the mouth.
n.o. Nephridial surface.
n.o., Nephridial opening.
o.t., Bases of outer tentacles.
V. Anterior surface.

In some species (figs. 2, 3) the two ends of the lophophore are rolled into spirals. An oral view of this region (fig. 2) shows: the mouth (m), continuous on either side with the groove between the two series of tentacles; the anus (a), in the middle line, at no great distance from the mouth; a transversely elongated epistome (ep), between the mouth and the anus; and, in the concavity of the lophophore, the apertures of the nephridia (n.o.) which, according to De Selys-Longchamps, open into the two large sensory or glandular “lophophoral organs” the orifices of which are seen at gl. The mouth leads into the oesophagus, which extends straight down the body nearly to the aboral end or “ampulla,” where it dilates into a stomach, from which the ascending limb of the U-shaped alimentary canal passes directly to the anus. The coelomic body-cavity is divided by a transverse septum (fig. 3, 5) which lies near the bases of the tentacles. The praeseptal or lophophoral coelom is continued into each of the tentacles and into the epistome. The postseptal coelom is partially divided by a ventral mesentery which is attached along the entire length of the convex side of the loop of the alimentary canal (a, a″) and by two lateral mesenteries (a′) which further connect the oesophagus with the body-wall. Each nephridium is provided with either one or two funnels which open into the postseptal division of the coelom (ne f). The nervous system lies in the epidermis, externally to the basement-membrane. A general nerve-plexus probably exists over considerable parts of the skin, and there are special nervous concentrations in the region of the epistome and along a double crescent (N) which follows the parietal attachment of the coelomic septum. The part which lies at the base of the epistome is morphologically dorsal in position. It is said by Schultz (11) to develop, in specimens which are regenerating the lophophoral end, from an invaglnation of the ectoderm: and in this condition is compared by him with