Untitled

More Questions and AnswerstfosflA uhoat DyesBy ALBERT C. jUDEOur popular contributor on the fascinating subject of animal geneticssustains the growing interest in the scientific aspects of cat breeding withthis sixth instalment in a fine new series. Readers are invited to submittheir'simple.problems to Mr. Jude who will be pleased to answer themfor the general interest in ensuing isrues.What facts are known about thegenetics of eye-colour?As far as I am aware, genetics o{eye-colour in cats has not beenu'orked on separately, but the follorvingobservations may be of interest.The colour of the eye dePends onthe pigment in the iris. In sorneeyes there is pigment on both sidesof the iris, on the side tacing theretina and on the side rvhich Iacesoutw-ard. Other eyes have Pigmentonly on the retinal side. In the latterclass there are the blues and cleargreys ; whiie the eyes rvith Pigmentin front of the iris also are browns,hazels or greens in various shades,according to the amount of pigmentpresent. Pigment is entirely absentin the eyes of albino animals, and asthe tiny l;loocl vessels are notobscured the iris takes on a pinkisha.ppearance.The instances in rvhich the pigmentic nresent in front of the iris areclominant to those in which it isabsent from tl-re front of the iris.Rrorvns hazcls ,,r orccns maled 1oco*harmo' i{ h-lprn.rron,r- oitp rh'.""fb".':b.'-.,.-recessive b1ue, but u'hen blues aremated together no individuais of thebrorrn class appear. Blues, hon'ever,may carry factors n'hich t'ill rnodifyl,rnrr ne trnr inctannp r {"^,^. -. "be cairied by blues rvhich t'il1 intensi[ythe bri)\rn pigment, and rn eyervith very little bron'n pigment matedrvith certain blues produces progenyof 3, deep brorvn, far deeper, maybe,than that in the e1'e of the brorvneyedparent,Orrite likclv there are other factorsu'hich modi{y brorvn, but not enoughis yet knou'n about the inheritance o{the shades to make possible any statementexcept that the heredity of thepigment in front of the iris behavesas though it rvere due to a Mendelianfactor. Th:t, hou'ever, is of importance,for it does suggest that presentsystems of classification of eye-colourszrre on rather an unsatisJa"ctory basis.Depth of co,our and shade is at presentthts accepted arrangemcnt, start.rvith the pa)e greys and ending uiththe brou'ns.The lighter qrecns arr place I amongthe blues. It is knorvn, hou.ever,thal Llrcs mav diffpr {rnm thp deenl,ro\\'ns in the absence o{ on}y onefactor, but the difierence betrveen ablue and a green rnav be :L dilTerenceclue to more than one factor.My queen recently had four normallyhealthy kittens and one rvhichwas bcrn with both eyes partiy open.WilI you piease explain this eye condition?In normal circumstances, the eyelidsof kittens are joined up beforebirth by a briclge of epjLhelium. 'lheL4