199 



1i: ntinx, mii>ic, and prophecy. The great Achilles 

 iiiul other I.eroes woe lii> ]ni]iil8. He died by being 

 accidentally wounded by one of the poisoned arrows 

 ut' liis friend Hercules. 



riiiroptero. See BAT. 



4'lliril. "i I' \\TII M.ni-s (Antilone /todgsoni), a 



-peri.--. ,,i antelope, inhabiting the pine-forests 

 and elevated open plains of Tibet, in regions Inirder- 

 ing on tin- snow-line. It is much larger than the 

 chamois, being iiliniit live feet in length, and three 

 I.-- i liij^l, a t the shoulder. Tin- colour is reddish- 

 fawn with some Mack. The eliirn lives in great 

 herds, and seems to exceed almost all the other 

 gregarious ruminants in watchfulness against the 

 approach of danger. They often lie concealed in 

 holes \\ liirli they make among the stones. 



C'hislclliirst, a village in Kent, 11 miles SE. of 

 London. Sir Nicholas Bacon was a native. Camden 

 I'ark estate (now built over) was the residence of 

 William Camden. Napoleon III. died at Camden 

 Place in 1873; his remains, with the Prince 

 Imperial's, were removed to Farn borough in J888. 

 'There are an Orphanage, a Governesses' Benevolent 

 In-titution, and a golf-course (1894) here. See 

 History by Webb, Miller, and Beckwith ( 1900). 



Clliswick. a suburban parish of Middlesex, on 

 the north bank of the Thames, 7 miles W. by S. of 

 St Paul's. Here are some charming old river-side 

 houses ( one of them William Morris's home ) ; 

 here too are extensive market-gardens to supply 

 London, and the gardens of the Horticultural 

 Society. In the churchyard are Hogarth's grave 

 and Foscolo's cenotaph ; and at the Duke of 

 Devonshire's beautiful villa, Chiswick House, died 

 Fox and Canning. Pop. (1861) 6505; (1881) 

 15,975; (1891)21,964. See Harper's for August 1888. 



4 'hi I aid rim. the chief town of Chitaldrug 

 district, Mysore, India, 126 miles NW. of Banga- 

 lore, with manufactures of coarse blankets and 

 cotton cloth. The military cantonments have been 

 ..abandoned on account of their unhealthiness. Pop. 

 4271. The district is the least populous in the 

 Mysore State, in which it is distinguished for its 

 low rainfall (10 to 25 inches) and arid, stony soil. 

 Area, 3994 so. in. Pop. (1871) 531,360; (1881) 

 376,310 the decrease being due to the famine of 

 1876-78; (1891) 413,984. 



Cllitin, the substance which forms most of the 

 hard parts of jointed-footed animals ( arthropods ), 

 such as crustaceans, insects, and spiders. It 

 was discovered by Odier in 1823, but regarded 

 erroneously as free from nitrogen ; rediscovered 

 by Lassaigne in 1843; and since then recog- 

 nised in all the four chief classes of arthropods 

 and in some other types. Huxley has given 

 -an account of its formation in the crayfish. 

 Chitin has been demonstrated in many arthropods, 

 also in the pen of cuttle-fishes (Mollusca), and 

 in the stalk and shell of l.imjnln <nnithia, a 

 brachiopod. Its presence is at least probable in 

 many other cases. In arthropods it is not con- 

 fined to forming the firm and often very hard 

 exoskeleton, but occurs internally in supporting 

 plates, &c. among the tissues. In the crayfish 

 it seems even to form the sheath of the strong 

 ventral nerves. In arthropods the greater portion 

 of the gut is formed as an intueking of the outer 

 skin (ectoderm) from in front and behind, and the 

 resulting portions known as fore- and hind-gut are 

 also lined by this chitin, which frequently exhibit 

 special internal thickenings for food -grinding pur- 

 poses. The chitinous coating or cuticle is formed 

 from underlying skin cells. In some cases the 

 epidermic cells probably sweat it off after the 

 manner of other secretions ; but Huxley has shown 

 -in regard to the crayfish that the superficial portion 



of the cells undergoes a chitinou* modification, 

 being literally turned into chitin. The outer 

 coat- of Crustacea is hardened by the addition of 

 calcium carlxjnate or phosphate, especially the 

 former ; such calcareous lianlening is very rare in 

 insects, but copper has been demonstrated in some 



beetle. CUticleg. 



Chitin is an amorphous white substance. It 

 ci ni tains nitrogen, but is free from sulphur. Its 

 resistance to acids and alkalies is very great ; it is 

 unaffected by digestive ferments, by water, hot or 

 cold, by alcohol or ether. It may be dissolved by 

 strong mineral acids (hydrochloric or sulphuric ), 

 and prepared from the cleaned exoskeleton of a 

 lobster, or better still from the pen of a squid. 

 Chemically it is regarded as a derivative of carbo- 

 hydrates, and may be split up into sugar and 

 glycosamin. According to Leduerhose, its formula 

 is CjaHjaNijOjo ; according to Sundwik, ('^H^NgO,, 

 -f TiHoO. See Krukenberg, Vergleichend-physio- 

 loffiscne Vortrdge ( 1886). 



Chiton* a genus of marine molluscs, type of an 

 important sub-class which may be regarded as 

 introductory to gasteropods. Unlike the lop-sided 

 snails, the chitons are bilaterally symmetrical. 

 The head is at the anterior end, the anus posterior ; 

 the 'foot' occupies the whole of the ventral surface ; 

 the heart, the gills, the excretory tubes, the genital 

 ducts, all exhibit the same symmetry. This marked 

 contrast to the gasteropods proper is further sup- 

 ported by the disposition of tne two important 

 nerve cords (pedal and visceral) which run parallel 

 to one another along the body. In some forms 

 there are numerous eyes, which occur, however, not 

 on the head, but on the body. Another striking 

 feature is the presence of a series of eight shelf- 

 plates along the back. On these and other grounds 

 the chitons are separated from gasteropods proper, 

 and established as a separate order, on which the 



Chiton elegans. 



name Polyplacophora, alluding to the multiple 

 shell-plates, has been bestowed. Nor is the order 

 a small one. Of the genus Chiton alone over 400 

 species have been recorded, and other smaller genera 

 are also distinguished. The British species are 

 small; those from warmer climate- sometimes 

 measure 3 to 4 inches in length. They are un- 

 doubtedly representatives of a primitive tyj>e, and 

 include numerous fossil forms from the Silurian 

 onwards. They are not, however, the simplest 

 gasteropods, for a few other forms, known it is 

 true with less fullness, exhibit the same essential 

 features in even simpler expression. These are ( a ) 

 the Neomenin?, including the genera Neomenia 

 and Proneomenia, and (b) the single genus Ch:eto- 

 derma. The systematic import of these last forms 

 has l>een emphasised by Professor Hiibrecht (Quart. 

 Jour. Micr. bci. 1882).* Along with the chitons they 



