. The wonder of life . les is in some measurelatent in the females, as is shown in cases where an oldfemale bird, or one with an abnormal ovary, begins to puton a masculine dress. The mascuhne characteristics are,as it were, seeds which wiU not normally develop exceptin male soil. They are parts of the inheritance, but theydo not start developing except in appropriate soil and inresponse to appropriate stimulus. It has been shownexperimentally that the stimulus, in some cases at least,is furnished by the hormones or internal secretions of thereproductive organs which are diffused by the blood
. The wonder of life . les is in some measurelatent in the females, as is shown in cases where an oldfemale bird, or one with an abnormal ovary, begins to puton a masculine dress. The mascuhne characteristics are,as it were, seeds which wiU not normally develop exceptin male soil. They are parts of the inheritance, but theydo not start developing except in appropriate soil and inresponse to appropriate stimulus. It has been shownexperimentally that the stimulus, in some cases at least,is furnished by the hormones or internal secretions of thereproductive organs which are diffused by the blood through-out the body when the organism becomes adolescent orwhen the breeding season sets in. It is interesting to find Fig. 88.—^^K)w-water marine ani|fiHls with bright colours. Tusk Shelpjp^teliupa. -2. Chiton. 3. ^P^r sepositus, (.^^e|*Ludwig;). 4. Sea Cucumber, ,^^jmone, Actinia mesembj3^nthemumi.;,(/l/ier,^;Andres.)6. ^msfer of AscidiaAi f. Small Cuitl^fisl^r Sepidba^ij/^terJatta.) ^^. THE WONDER OF LIFE 551 many cases, pheasants, iti which the brilUant color-ation, which is in most cases nuptial, is a constantmasculine character. In Summary.—^The poiat that we wish to emphasizefjm this brief survey of animal coloration is, that the pigmentsubstances are primarily waste-products, reserve-products,or by-products of the animals metabohsm, and that inmany cases the colours have no more significance for theirpossessors than the gorgeous autumnal tints of witheringleaves have for the tree—that is to say, none ! Similarly,the structural features that cause iridescence and the hkeare primarily the ripple-marks of growth. Likewise, inmany cases, it seems probable that the colouring of specialparts of the body is due to particulate conditions in differentparts. Just as green vivianite may be deposited in thebones of a gar-pike, because of certain physiological con-ditions, so an island on the skin, the tip of an ear, the endof a tail may have
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