feast is largely shared by unbidden guests. Not to speak of insects which feed upon the pitcher itself, some drop their eggs into the putrescent mass, where their larvae find abundant nourishment, while birds often slit open the pitchers with their beaks and devour the maggots in their turn.
Cephalotus follicularis, a native of south-west Australia, a small herbaceous plant, bears ordinary leaves close to the ground as well as pitchers. The latter somewhat resemble in general form those of Nepenthes. The lid is especially attractive to insects from its bright colour and honey secretion, three wings lead up to the mouth of the pitcher, on the inside of which a row of sharp spines points downwards, and below this a circular ridge (r, fig. 3) armed with papillae serves as a conducting area. A number of glands on the interior of the pitcher secrete a plentiful fluid which has digestive properties. Comparison with monstrous forms shows that the pitcher of Cephalotus arises by a calceolate pouching from the upper surface of the ordinary spathulate leaves, the lid here arising from the proximal side of the pitcher-orifice.
PITCHSTONE (German Pechstein, from its resemblance to
pitch), in petrology, a glassy igneous rock having a resinous
lustre and breaking with a hollow or conchoidal fracture. It
differs from obsidian principally in its rather dull lustre, for
obsidian is bright and vitreous in appearance; all pitchstones
also contain a considerable quantity of water in combination
amounting to from 5 to 10% of their weight or 10 to
20% of their volume. The majority of the rocks of this
class occur as intrusive dikes or veins; they are glassy forms
of quartz porphyry and other dike rocks. Their dull lustre
may be connected with the great abundance of minute crystallites
and microlites they nearly always contain. These are
visible only in microscopic sections, and their varied shapes make
pitchstones very interesting to the microscopist. Although
pitchstones are known which are of Devonian age (e.g. the
glassy dacite of the Tay Bridge in Fife, Scotland, and the
andesite-pitchstones of the Cheviot Hills), most of them are
Tertiary or recent, as like all natural glasses they tend to crystallize
or become devitrified in course of time. In some of the
older pitchstones the greater part of the mass is changed to
a dull felsitic substance, while only nodules or kernels of
unaltered glass remain.
Some pitchstones are very acid rocks, containing 70 to 75% of silica, and have close chemical affinities to granites and rhyolites. Others contain more alkalis and less silica, being apparently vitreous types of trachyte or keratophyre; others have the composition of dacite and andesite, but the black basaltic glasses are not usually classified among the pitchstones. Very well known rocks of this group occur at Chemnitz and Meissen in Saxony. They are brown or dark green, very often perlitic (see Petrology, Plate I., fig. 5), and show progressive devitrification starting from cracks and joints and spreading inwards through the mass. For a long time the pitchstone dikes of Arran in Scotland have been famous among geologists for the great beauty and variety of skeleton crystals they contain. These pitchstones are dull green in hand specimens. Some of them contain phenocrysts of felspar, augite, &c.; others do not, but in all there is great abundance of branching feathery crystalline growths in the ground mass they resemble the branches of fir trees or the fronds or ferns, minute crystalline rods being built together in aggregates which often recall the frost patterns on a window-pane. It is supposed that the mineral they consist of is hornblende. In addition to these larger growths there are many small microlites scattered through the glass, also hair-like trichites, and fine rounded globulites. When phenocrysts are present the small crystals are planted on their surfaces like grass growing from a turf-covered wall. These pitchstones are believed to proceed from the great eruptive centres which were active in western Scotland in early Tertiary times. Another pitchstone of the same period forms a great craggy ridge or scuir in the island of Eigg (Scotland). At one time regarded as a lava flow occupying an old stream channel it has recently been described as an intrusive sheet. It is from 200 to 300 ft. thick. The rock is a dark, nearly black, pitchstone-porphyry, with glancing idiomorphic crystals of felspar in a vitreous base. It contains no quartz; the felspars are anorthoclase, and with them there are numerous crystals of green augite. The ground mass contains small crystallites of felspar, and is of a rich brown colour in thin section with well developed perlitic structure (see Petrology, Plate II., flg. 1). In chemical composition this rock resembles the trachytes rather than the rhyolites. In Eigg and Skye there are many dikes of pitchstone, mostly of intermediate rather than of acid character, all connected with the great eruptive activity which characterized that region 1n early Tertiary times.
The following analyses give the chemical composition of a few well-known pitchstone:—
| SiO2 | Al2O3 | Fe2O3 | MgO | CaO | Na2O | K2O | H2O | |
|
I. Meissen, Saxony . . . . |
72.42 |
11.26 |
0.75 |
0.28 |
1.35 |
2.86 |
3.80 |
7.64 |
The first two of these contain much water for rocks the ingredients of which are but little decomposed. They are of acid or rhyolitic character, while the third is richer in alkalis and contains less silica; it belongs more naturally to the intermediate rocks (or trachytes.) (J. S. F.)
PITESCI (Pitesti), also written Pitesti and Pitest, the
capital of the department of Argesh, Rumania, situated among
the outlying hills of the Carpathians, on the river Argesh, which
is here joined by several smaller streams. Pop. (1900), 15,570.
The surrounding uplands produce good wine, fruit and grain,
besides being rich in petroleum and salt, and, as the main
Walachian railway is met at Pitesci by lines from Câmpulung
and Hermannstadt in Transylvania, the town has a considerable
trade. It has manufactures of lacquer and varnish.
PITH (O.E. pitha, cognate with Du. pit, kernel of a nut), properly the medulla, the central column of spongy cellular
tissue, in the stems of dicotyledonous plants (see Plants:
Anatomy). The word is thence applied to the spinal cord or
marrow in animals, to the medullary end of a hair, and to
that which forms the central part or core of any object or
substance; hence, figuratively, vigour, energy, concentrated
force. Very light hats or helmets are made of the dried pith
of the Indian sponge wood or hat plant (Aeschynomene aspera,
the native name being Solah). These pith hats are worn by
Europeans in India and the East. The Chinese Ricepaper-tree
(Aralia or Fatsia papyrifera), from the pith of which the delicate
white film known as “rice-paper” is made, is also known
as the pith-plant.
PITHECANTHROPUS ERECTUS (Erect Ape-Man), the
name given by Dr Eugene Dubois, of the Dutch army medical
service, to the imaginary creature which he constructed from fossilized remains found by him in Java. These fragments consisted of a thigh-bone, two teeth, and the upper part of a skull, and were unearthed in 1891–1892 on the left bank of the Bengawan River near Trinil. The skull appears to have been low and depressed with strong supraciliary ridges; the teeth are very large, and the femur is quite human. The teeth and skull were found together, the femur a few yards away a year
afterwards. The discoverer, however, stated it as his belief
that the fragments were portions of the same skeleton and
belonged to a creature half-way between man and the higher
apes and of the Pleistocene age. Much discussion followed the
“find,” and many authorities have given an opinion adverse to
Dr Dubois’s theory. The prevailing opinion is that the bones
are human. They are not held to represent what has been
called “the missing link,” bridging over the gulf between man
and the apes, but almost all authorities are agreed that they
constitute a further link in the chain, bringing man nearer his Simian prototype. L. Manouvrier concludes that Homo javanensis walked erect, was of about medium height, and was a true precursor, possibly a direct ancestor, of man. He calls attention to the fact that the cranial capacity decreases in proportion to the antiquity of the human skulls found, and that the pithecanthropus skull has a capacity of from 900 to 1000 cc—that is, “stands at the level of the smallest which have been occasionally found amongst the reputedly lowest savage peoples.”
See Dubois, Pithecanthropus erectus (Batavia, 1894); a later paper read by Dr Dubois before the Berlin Anthropological Society was translated in the Smithsonian Report for 1898 Also a paper read by Dr D. J. Cunningham before the Royal Dublin Society, January 23, 1895 (reported in Nature, February 28, 1895); O. C. Marsh,
