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Show 14 HEXUAL SET.JECTION. P .\llT 11. "orange-coloured stripes, which give it tho appearance " of a Labrus, and the body part::.tkcs of a golden-orange "tinge. rrhe females arc dark in colour, and arc com- " monly called black-fi.sh." 20 • An analogous. and oven O'reater chano-e takes place with the Sctlmo et·wx or bulltrout; the ;ales of the char (S. tbmbla) are likewise at this sea on rather brighter in colour than the females? The colours of the pike ( Esox reticulal'LbS) of the U nitecl States, especially of the male, become, during the breeding-season, exceedingly intense, brilliant, and iridcscent.:.! Z .. \.nother striking instance out of many is aiTordccl by the male stickleback (Gasterosleus leim·us), which is described by 1\Ir. vVarington,23 as being then •: beautiful beyond description." Tho back and eyes of the female are simply brown, and the belly white. The -eye. of the male, on the othrr hand, are "of the most " splendid green, having a metallic lustre like the "green feathers of some humming-birds. rrhe throat "' and belly are of a bright crimson, the back of an "ashy-green, and the whole fish appears as though it ~'wore somewhat translucent and glowed with an in,, temal incandescence." After the breeding-season thc.·e colours all change, the throat and belly become of a paler red, the back more green, and the glowing tints subside. That with fishes there exists some close relation between their colours and their sexual functions we can dearly see ;-firstly, from the adult males of certain species being differently coloured from the females, and often much more brilliantly ;-secondly, from these same 2o Yarrcll, 'British Fishes,' vol. ii. 183G, p. 10, 12, R5. ~~ "\V. Thompson, in 'Annn.ls am.ll\iag. o( Nat. History,' vol. vi. 1841, Jl. ·l-1.0. ~~ 'The American Agriculturist,' 18G8, p. ·100. n 'Annals and 1\fn.g. of Nut. lli~t.' Oct. L8:J2. (;JIAP. XII. l!'ISIIE::l. 15 males, whilst immature, resembling the mature females; -;-':nd, lastly, from ~he males, even of those species "hiCh a~ all other times of the year are identical in col~ur w1th the females, often acquiring brilliant tints durmg the spawning-season. We know that the males ~.re ardent in their courtship and sometimes fight despeHttely together. If "·e may assume that the females have th~ power of exerting a choice and of selecting the more h1ghly-ornamcntec1 males, all the above facts beco~e intelligible through the principle of sexual selectwn. On the other hand, if the females habitually deposited m~cl left their om to be fertilised by the first male \VhlCh chanced to approach, this fact would be fatal to the efficiency of sexual selection . for the.rc could be no choice of a partner. But, a~ far ~ls Is known, the female never willingly spawns except m ~~e close presence ef a male, and the male never fertlhses the ?va except in the close presence of a ~emale. ~t JS obviously difficult to obtain direct evi~ence With respect to female fishes selectino· the1r partners. An excellent observcr,24 who carefull; watched the spa,:ning of minnows (Oyprinus phoximts) remarks that owmg to the males, which were ten time~ as numerous as the females, crowding closely round ~'h~m, he conld "speak only doubtfully on their opera-tiOns. When a female came among a number of ~: ~ales they imn:ediately pursued her; if she was not '· I.eady for shecl.clmg her spawn, she made a precipitate " Ietreat; but If she was ready, she came boldly hi "among them, an~ was immediately pressed closely by " a. mal~ on each SI~e ; and when they had been in that situatwu a short time, were superseded by other two " who wedged themselves in between them and th~ ~., Louuou':; 'Mag. of Nnt. Hi:::.t.' \'Ol. v. 1832, p. G8l._ |