Page:EB1911 - Volume 22.djvu/692

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676
PYATIGORSK—PYCNOGONIDA

had called him the “ aristocrat of the democracy.” He joined Ledru-Rollin in the attempt of the 13th of June 1849, after which he sought refuge in Switzerland, Belgium, and finally in England. For a glorification of regicide on the the Orsini attempt against Napoleon III. he was brought before an English court, but acquitted, and the general amnesty of 1869 permitted his return to France, but further outbursts against the authorities, followed by prosecution, compelled him to return to England. The revolution of the 4th of September brought him back to Paris, and it was he who in his paper Le Combat displayed a black-edged' announcement of the pourparlers for the surrender of Metz. After the insurrection of the 31st of October he was imprisoned for a short time. In January 1871, Le Combat was suppressed, only to be followed by an equally virulent Vengeur. Elected to the National Assembly, he retired from Bordeaux with Henri Rochefort and others until such time as the “parricidal ” vote for peace should be annulled. He returned to Paris to join the committee of public safety, and, in Hanotaux's words, was the time ulcérée of the Commune, but was blamed for the loss of the fort of Issy. He was superseded there by Delescluze, but he continued to direct the violent acts of the Commune, the overthrow of the Vendome column, the'destruction of Thiers's residence and of the expiatory chapel built to the memory of Louis XVI. He escaped the vengeance of the Versailles government, crossed the frontier in safety, and, though he had been condemned to death in his absence in 1873, the general amnesty of July 1880 permitted his return to Paris. He was returned to the Chamber of Deputies for the department of Bouches-du-Rhone in March 1888 and took his seat on the extreme Left, but died at Saint-Gratien on the 3rd of August 1889.


PYATIGORSK, a town and watering-place of Russian Caucasia., in the province of Terek, 141 m. by rail N.W. of Vladikavkaz. Pop. (1882), 13,670; (1897), 18,638. It owes its origin to its mineral waters, which have long been known to the inhabitants of Caucasia. The sulphur springs, about fifteen in number, come from a great depth, and vary in temperature from 75° to 96° F.; they are used both for drinking and for bathing. The first buildings were erected in 1812, and in 1830 the name of Pyatigorsk (“ town of the five mountains ”) was given to the new settlement. Its subsequent rapid increase was greatly stimulated by the completion of the railway connexion with Rostov-on-the-Don. The town is charmingly situated on a small plateau, 1680 ft. above sea-level, at the foot of the Beshtau, Mashuk and three other outliers of the Caucasus range, which protect it on the north. The snow-covered summits of the Elbruz are visible to the south. The most noteworthy features are a cathedral, a monument to the poet M. Y. Lermontov (1814–1841), and a hydropathic.


PYCNOGONIDA, or Pantopoda, marine Arachnida (q.v.) remarkable for the reduction of the opisthosoma or abdomen to an insignificant tubercular or rod-like process (whence their trivial name of “ nobody crabs ”), and for the development of the oral region into a relatively immense suctorial proboscis. They form a compact group, differing from all the other orders of Arachnida in certain structural characters of such morphological importance that it is impossible to affiliate them closely with any group of that class. For instance, in all typical existing Arachnida the ganglionic centres which innervate the ambulatory appendages are coalesced to form a single nervous mass, whereas in the Pycnogonida the ganglia supplying these limbs retain their original distinctness. More important still is the circumstance that in the Pycnogonida there may be as many as seven pairs of leg-like limbs behind the mouth; but in the typical Arachnida there are never more than five such pairs. Curiously enough, too, although the number of these appendages, in all the orders of typical Arachnida is, with the exception of some degenerate Acari, a quite constant character, the number in the Pycnogonida is very variable. In most cases there are four pairs of ambulatory limbs, but in two antarctic genera, namely Pentanymphon, belonging to the family Nymphonidae and Decalopada, probably belonging to the Colossendeidoe, they occasion of are increased to five pairs. In front of these four or five pairs of ambulatory limbs there may be two pairs of longish post-oral limbs, called respectively the ovigerous legs and the palpi; but these may be totally absent. Finally, the single pair of pre-oral appendages may be well developed, three-jointed and chelate, or reduced in size and complexity, or altogether suppressed.

7 FIG. 1.-Male of Pycnogo'/zum littoral, Müller. a, Parts of mouth forming a c, c, Thoracic segments. beak, d, Rudimentary abdomen.

b, Cephalic area. e, Eyes.

FIG. 2.-The same; under size.

a, a, Ovigerous legs.

As examples of this class exhibiting extremes of variation in the development and reduction of the appendages may be cited Decalopoda, which has the full complement of eight pairs of appendages, and the female of Pycnogonum littorale, in which all the appendages are aborted save four pairs of ambulatory limbs. -

All the principal organs of the body are concentrated in that part which bears the appendages. The generative glands are lodged on each side, sending prolongations into the appendages, and their ducts open upon the second segments of more or fewer of them. The alimentary canal, beginning with the mouth at the extremity of the proboscis and terminating with the anus at the extremity of the tail-like opisthosoma, also sends long saccular prolongations into the limbs. Food is imbibed by means of the suctorial pharynx lodge in the proboscis, the sucking action being effected by means of muscles radiating from the wall of the pharynx to that of the inner surface of the exoskeleton of the proboscis. The circulatory system, where it has been observed, consists of a heart formed of about three chambers communicating with each other. In each chamber there is a pair of orifices for the entry of the blood; and the fluid is expelled through an orifice at the anterior extremity of the first chamber. No organs of respiration are known, the integument being the medium for the oxygenation of the blood. The sexes are distinct, but commonly there is little external difference between the males and the females. Sometimes the female is considerably the larger of the two; and frequently the ovigerous legs are less well developed than in the male. Sometimes indeed these limbs are entirely wanting in the female, whereas this is never the case in the male. Finally, in the 'females the generative orifices are much more conspicuous than in the males, and the fourth joint of the legs is often swollen. The invariable presence of the ovigerous appendages in the males is correlated with the habit practised by this sex of carrying the fecundated eggs. The eggs are usually aggregated in two spherical masses round the middle of each of the ovigerous legs; sometimes, however, there are two such masses on