750 



HOLOTHURIANS 



HOLT 



organs consist of auditory vesicles situated near the 

 anterior end of the body, and containing small cal- 

 careous corpuscles (otoliths), and of the tentacles 

 above mentioned. These may be either simple or 



a, Semidiagrammatic view of the viscera of a Holothurian be- 

 longing to the Aspidochirotse. Projecting from the upper end 

 are the tentacles, lower down the calcareous ring, and still 

 lower in the middle line the two Polian vesicles. The intestine 

 is shown passing in a loop to the hinder end of the body ; dur- 

 ing part of its course it is seen to be attached to the body- wall 

 by a mesentery. Two respiratory trees open into its expanded 

 termination or cloaca, which is connected to the walls of the 

 body by radiating Tnuscular bands. Longitudinal muscles 

 pass from the anterior to the posterior end of the animal. To 

 the right is the branched genital gland with its duct. (From 

 Leunis.) 



6, Phyllophorus urna, one of the Dendrochirobe, ^d nat. size (from 

 Leunis) ; c, Holothuria tubulnsa, one of the Aspidochirotee, 

 |th nat. size (from Leunis) ; d, Oneirophanta mntabilis, one of 

 the abyssal Elasipoda, Jd nat. size (from Theel) ; e, calcareous 

 wheel, from the integument of Chirodota purpurea, magnified 

 100 diameters (from Theel) ; /, g, plate and anchor of Synapta 

 Beselii, highly magnified (from Theel); h, larval form 

 (Auricularia) of Holothuria tubulosa, highly magnified (from 

 Selenka). 



branched, and in a few cases they are furnished 

 with suckers. In the Elasipoda tactile organs are 

 present in the form of dorsal papillae. 



The generative organs consist of a bunch of tubes, 

 with one end closed ; their duct opens either within 

 or just outside the circle of tentacles. The egg 

 develops as a rule into a curiously -formed bilaterally 

 symmetrical larva, formerly described as a distinct 

 animal under the name Auricularia. In a few 

 cases the development is direct ; in Cucumaria 

 crocea the young are borne among the tentacles of 

 the parent, whilst in Psohis ephippifer they are 

 carried in a special pouch on the back! 



The class is subdivided as follows : 



I. ELASIPODA, primitive deep-sea forms : bilaterally symmetri- 

 cal; tube feet on the ventral surface, papilte on the 

 dorsal. No respiratory trees. A very large munber of 

 genera and species have been obtained by the Challenger 

 and other deep-sea expeditions. 

 IJ. PEDATA, with well-developed tube-feet and papillse. 



(1) Aspidochirotse, with tentacles bearing a disc, and ten 



calcareous plates round the gullet. The genus 



Holothuria as now understood belongs here. 



(2) Dendrochirotae, with arborescent tentacles 



e.g. Cucumaria, Psolus. 



III. APODA, devoid of tube-feet and papilla. 



(1) Pneumonophora, with respiratory trees e.g. Mol- 

 padia. (2) Apneumona, with neither radial water- 

 vascular canals, respiratory trees, nor Cuvierian 

 organs e.g. Synapta, Chirodota. 



The Holothurians are all marine, and have a 

 world-wide distribution ; traces of them have been 

 found fossil as far back as the Carboniferous 

 deposits of Scotland. They either take in large 

 quantities of sand and absorb the nutritive matters 

 mixed with it, or devour small animals. On strong 

 contraction, caused by sudden irritation, the whole 

 digestive canal and its appendages are not unfre- 

 quently ejected ; but these are regenerated after a 

 time. In some species the cloaca is inhabited by a 

 small parasitic fish of the genus Fierasfer. Tre- 

 pang (q.v. ), or beche-de-mer, a great delicacy among 

 the Chinese, consists of dried Holothurians. 



Holsteill, formerly a duchy belonging to 

 Denmark, and at the same time a member of the 

 Germanic Confederation, was annexed in 1866 to 

 Prussia, which incorporated it in the province of 

 Sleswick-Holstein. It is separated from Sleswick 

 on the N. by the river Eider and the North Baltic 

 Canal ; is bounded on the E. by the Baltic Sea, the 

 territory of Liibeck, and the duchy of Lauenburg ; 

 on the S. by the Hamburg territory and the Elbe ; 

 and on the W. by the North Sea. One-eighth of 

 the surface consists of marshes. The central dis- 

 tricts are occupied by an undulating plain traversed 

 from north to south by a low heathy and sandy 

 ridge. The soil, with the exception of several 

 tracts of sand and heath, is very fruitful, especially 

 in the marshes. The climate and natural produc- 

 tions closely resemble those of similar districts in 

 the north of Germany. Salt and gypsum are the 

 only minerals found. Peat is plentiful. Agricul- 

 ture and the rearing of cattle are the chief employ- 

 ments, though market-gardening flourishes in the 

 neighbourhood of Altona and Hamburg, and ship- 

 ping in the seaport towns, and fishing along the 

 coasts, especially for oysters in the North Sea. 

 Area, 3237 sq. m. ; pop. about 560,000 mostly 

 Germans of the Low German stock. The history 

 of Holstein will be noticed under SLESWICK. 



Ilolsten, KARL CHRISTIAN JOHANN, an eminent 

 Protestant theologian, born at Giistrow in Mecklen- 

 burg-Schwerin, 31st March 1825. He studied theo- 

 logy and philology at Leipzig, Berlin, and Rostock, 

 and became in 1852 a teacher at the Rostock gym- 

 nasium. In 1870 he was called to the Bern High 

 School as an extra-ordinary professor, next year 

 became ordinary professor, and in 1876 obeyed a 

 call to a similar post at Heidelberg. His startling 

 contribution to Pauline theology, Znm Evangelium 

 des Paul us und Petrus ( 1867 ), was followed by Das 

 Evangelium, des Paulus (vol. i. 1880), Die drei 

 urspri'mglichen, noch itngeschriebenen Evangelien 

 (1885), and Die Synoptischen Evangelien nach der 

 Form ihres Inhalts ( 1886). 



Holt, SIR JOHN, lord chief-justice of the Court 

 of King's Bench, was born at Thame in Oxfordshire, 

 on 30th December 1642. After leading a wild life 

 as a student of Oriel College, Oxford, he entered at 

 Gray's Inn, reformed his manners, and was called 

 to the bar in 1663. He figured as counsel in most 

 of the state-trials of that period, and generally as 

 pleader for the defendants. In 1666 he was made 

 recorder of London and king's serjeant, and was 

 knighted. On the accession of William III. he was 

 raised to the dignity of lord chief-justice of the 

 King's Bench, and filled the post to his life's end. 

 He died 3d March 1710. Sir John Holt occupies 

 an honourable place among the dignitaries of the 

 English bench on two accounts. Contrary to the 

 practice of his predecessors, he treated those who 

 appeared before him with uniform fairness and 

 justice. Although politically a Whig, Holt's judi- 



