PIGMENTS 



PIKE 



175 



Ponlton tliat surrounding colours modify those of 

 Koine caterpillars, and J. T. Cunningham has 

 demonstrated that young flat-fishes when illumined 

 on the normally shaded and unpigmented side 

 develop pigment-cells on that surface. 



But in regard to the internal conditions of the 

 formation of pigment we are more ignorant. 

 Their relation to the general metabolism of the 

 body is one of the unsolved problems of compara- 

 tive physiology. Some seem to be of the nature 

 of waste- products, a few are perhaps reserve sub- 

 stances, many may 1* called by-products of meta- 

 bolism. On the other hand it is well known that 

 many pigments are auxiliary to some of the im- 

 portant functions of the body. Thus, hsemoglobin 

 and analogous substances are important in con- 

 nection with respiration ; the chlorophyll of plants 

 ntially associated with assimilation ; the 

 figment* found in the eyes of animals seem to aid 

 in the visual function. 



Ert< i mil I 'I Hit i/ of Colouring. In many different 

 ways the colouring of animals is of importance to 

 their well-being in the struggle for existence. 

 Thus, the green insects and reptiles which live in 

 the grass or on trees, the sandy-coloured beasts 

 which are hardly to be detected against a back- 

 ground of similar colour, the white animals which 

 are almost invisible among the snow illustrate 

 protective colouring. This colour-resemblance 

 iietween animals and their surroundings is some- 

 times marvellously exact, and doubtless of great 

 advantage. Moreover, not a few animals, among 

 eiustaeeaiiH, fishes, amphibians, and reptiles, have 

 tin 1 power of changing their colour, for the pigment- 

 cells expand or contract under nervous stimulus, and 

 this 1 is in some cases advantageously protective. 

 The conspicuous colours of some unpalatable or 

 noxious animals may lie n expression of their 

 constitution, while, according to a theory of another 

 older, they warn off possible molesters. It may 

 also be that colours are sometimes useful in a-sist 

 ing mutual recognition lietween individuals, or in 

 indicating attitudes and movements. Finally, in 

 many animals the sexes ditl'er markedly in colour, 

 the males being almost always brighter than their 

 mates. According to some, tliis depends on the con- 

 stitutional |>ecnliarities of malenessand femaleness, 

 while Darwin hat emphasised that the brightness 

 of male* has been enhanced by the selective taste 

 of the females, and Wallace has urged that natural 

 selection has retarded female butterflies and' birds 

 from attaining a brightness which would expose 

 them during the weakness or preoccupation of 

 the reproductive period to the hungry eyes of 

 their enemies. But our recognition of tile way 

 in which variations of colouring are fostered or 

 eliminated in the course of natural selection must 

 not lead us to forget the primary problems of the 

 origin of the pigments, and of the physiological 

 conditions which determine their distribution. 



KII.K, BLOOD, CATERPILLARS, CHLOROPHYLL, 

 ENVIRONMENT. FLOWER, MIMICRY, SEX, and S K\IAI, 

 SKI.KITION. C. Kr. W. Knikenberg in his Grundziir/e 

 tintr vr.T(ileirhcndtn Pht/tiologie der Farbxtoffe unrt tier 

 Farbm (Heidelberg, 1884) has given an admirable 

 account of the animal pigments, with a bibliography of 

 important researches, sucli as those of Kiihne. MacMiinn, 

 .Mosel.-y, and .">orby. See also M'Kendrick, Text-book 

 'if I'liiitiiilmiii (1888); Halliburton, Ph.iifiiituiiifnt and 

 l',itli,,h,.,,, ,,i <;htmittry ( 18.il ). For the relation between 

 cdour and the external conditions of life, see Semper's 

 /,i// ( Inter. Sc. Series, IK81 ) ; and for the import- 

 :im,v of colour in the external life of animals, Poulton's 

 <;,l,,nr* iif Animal (Inter. Sc. Series, 1890). 



PigWtt, KirilAKIi. See I'AHNELL. 



Pike (Ktox luciun), a well-known fresh-water 

 fish abundant in the temperate parts of Europe, 

 Asia, and America. The body U long anil covered 

 with small cycloid scales ; the dorsal fin is near the 



tail ; the mouth is large, with strong, sharp teeth ; 

 the lips have no barbels ; the stomach is without 

 the usual pyloric appendages ; the open ( physosto- 

 matous) air-bladder is simple; the gill-aperture is 

 very wide. The fish is olive-gray above, silvery 

 white on the belly, and is mottled with pale spots : 

 iu length it may measure from 2 to 4 feet : and it 

 may attain a weight of 10 to 20 lb., or in rare 



cases, it is said, about 60. The genus includes 

 besides four or five other species, notably the 

 Mtiskullunge of the North American lakes, a 

 'grand game fish,' often 6 feet long, mi habit a 

 dauntless marauder. Another of smaller size (Esox 

 ritii-iilut us) is the common 1'ickerel of the eastern 

 states. All three are valuable food-fishes. 



The common pike or Jack (Scotch Gedd) is 

 said to spawn when three years old. The ova are 

 usually laid in March, biit the spawning is pro- 

 tracted. There is great mortality among the 

 young, which take about a week to hatch. Growth 

 is at first rapid, and continues more slowly for years. 

 The longevity of the fish is great, but the records 

 of pike which have attained to 250 years are as 

 unsatisfactory as the evidence for longevity usually 

 is. There is no doubt, however, that tliey may 

 outlive their keepers ; and it is also true that they 

 sometimes venture ashore, and that they sometimes 

 lie in a torpid slumber in the jiools. But the most 

 characteristic iiuality of pikes is voracity. Feeding 

 for the most part on frogs ami small fishes, they are 

 often prompted by hunger to bid for higher game, 

 such as ducks, geese, water-hens, and water-rats. 

 Thoreau describes the pike as the 'swiftest, 

 coarsest, and most ravenous of lislies, which 

 .bi-se.lyn calls the river-wolf. It is a solemn, 

 stately, ruminant fish, lurking under the shadow 

 of a lily-pad at noon, with still, circumspect, 

 voracious eyes ; motionless as a jewel set in water, 

 or moving slowly along to take up its position ; 

 darting from time to time at such unlucky fish 

 or frog or insect as comes within its range, and 

 swallowing it at a gulp. Sometimes a striped 

 snake, bound for greener meadows across the 

 stream, ends its unuulatory progress in the same 

 receptacle.' The Bony Pike (Lepidosteus) is a 

 Ganoid, and the name is sometimes applied to the 

 marine Gar-pike (Belone) and to some American 

 perches. See BONY PIKK, GAR-PIKE. 



See the articles ANGLING and PISCICULTURE ; Pennell's 

 Book of the Pike ('M ed. 1884) ; and Bickerdyke's Aruj- 

 linn for Pike (1888). 



Pike, a word loosely used for almost any kind 

 of lance or Spear (<j. v. ), whether larger or smaller 

 headed, as used by infantry troops, and now super- 

 seded by the bayonet. The naval boarding-pike is 

 a lance about the length of a man. The short 

 pike, called half-pike or s/mntoon, long carried by 

 some classes of" infantry officers in most European 

 armies, was a kind of Halbert (q.v.) with a smaller 

 but ornamented head, and was rather an emblem 

 of dignity than a fighting weapon. In 1804, when 

 a French invasion was threatened, pikes were dis- 

 tributed by government through the country ; and 

 the secret manufacture of iron pike-heads was one of 



