MENDEL'S LAW.

Dominion, Volume 1, Issue 159, 30 March 1908, Page 2

MENDEL'S LAW.

AN AID TO PLANT BREEDERS. how to get Blight-proof seeds. The "Dental Record '' is-scarcely a- book, in which one would expect to- find an article of t-echnioal interest to farmors..- Yet the January issue, of • that publication ' con-, tains a valuable contribution on " Mendeljs Law of! Inheritance." ' It is- by J. F. Colyer,: L.R.C.P.v M.8';0.5., L.D.S., The article devotes itself, to 1 explamihg' what' Meiidcl's , lawis; and how it is-applied." 'Farmers who de-' sire to experiment'in ." raising rust-resisting' 6<its,-blight-proof potatoes,, hnd such things, may lik'o'to know; l wbat'' i Meudol '.discovered 'f— ■ . If. wo take'.two', varieties of, the ohe with -liix ears -and l tho other "ivith . dense £ftrs, apj cross' themj . the hj-brid obtained, will bo-, found to" have ears neither .'as lax, as: the ono. pirent; nor as: ' dense as the other.. In pther ; , words, I 'theiv'ears may be described as-intermixliate'.':. Take and grow - , the. seeds from.' this, hybrid,, and watch; tho results'. The'offspring will be (a) lax-eared,-(b)-inter-mediates, .and ;'(c) ;,in' the following- proportion—'l:2:l. -There - will bo ,-rio other types:.. : Now'l6t us sow tho grain of this .second family- and . watcli -tho results. We .shall find -(a), ■tho.'.'grain'from the, las-: earod produces onlv lax-oared- wheat; ;the grain from-' tholnwrniaiiaip ■ produces .'(IV/ lax-eared, (2) intermediates, '(3)' dense-eared iri :tho proMrtion 'of 1'.:,2': 1; (c) the grain from: tlid. Miise-ifared produces 'only • defflseoared. ."' . . . : • " We; mitst .now 'cpnMdfer tho .explinatjon given to. '.thes3 faots'iby,; Moridcl-.'"{ln'. most' animals and r plants' the hew individual .is the result of a sexual process,' t-lio essential feature being the';fusion.' of the'female cell with that of tho male; These cells are called gametes,- "and when fusion- has' taken place tho rcslilting cell is. called a zygote.' ; Fromtho,zygote the uew individual is formed by repjat-ed coll : division; and;'during' tho pro-' ccss tho.;future .'genii "cells also afisoi', .These in turn ripen to 1 fohii-gametes,- and in them are,-:contained-all tho characters of the individual. Mrhdel,"as the.result.of his work,wis-: led to. the confeeptioii- of,''pairs of' unit. • characters.' ', : B_y- ,t-bis'-is meant'' black asopposed to white,'tallnesfe: to. shortness,'' ' laxity -'dcnsity,' 'etc.,;: tho 'pairs beiiig ;termed ; allelomorphs;,': In a single ganieto: one 'of -these characters may- be,, present-, ,hut . liot 'b6th. .•:"• ■;: "'■■.

".Lot us reiilrn to' tiio experiment, just recounted; Tho■ narent with densn ears would possess gametes containing only tho densa character, and tho parent/ with lux ©ays"; would: possess' gametes ■ .onjy lax oharacters; 'but?: tho'.hybrid l .or . iufcer-; ■mediate.;would/contain' gametes ''some,, con-', taming dorisaVand. some lax characters...-A zygote containing gametes .carrying tho- same.character /is'' called a' lidnwzygoto;. one containing' ganletss'- -cqrrying botfj characters a liet-erpzygotoi One step further in.order, to. ,underetand the "theory of ■Mendelalthough tho hj'brid; 'product /gametes',. of': two johar-V acters, it produces them in equal numbers. That is, oSoictly what experiment- proves, • / In some experiments, such as: with bearded and nori-bearcd wheats,' where tho hybrids a iynic ortd'particular parent (tho non-bearded ant), tlits term " dominant," is applied to ihb parent mimicked, and tho torm recessivo t4-:tno 'other, .Tho hvbridi however, contains gametes carrying each- character, and they appear in ;tho.;next generation. • Of tho.-.pro-.g6ny. those which'aro bearded produce alivays Warded -.offspring, : ,but ; ■ inV these which ' are ntm-bGardcd Some I .contain hidden the bearded 1 tondenfcjv and- varv m - tho l offspring Thus bearded:'secdsv(rccessive). can'.be',relied on:!to''" truo.i»' Tho >ojthers-,<canv bo s6!ecte<Mllownvtoil)reedr by,.-succes-sive experiments , The experiments wifclr wheat as .to resist-] ancs to ; yellpw^rusi/arp- of -great, interest!' American ruSt-p'roof.; and . dense-eared; 1 ' was crossed ...with'. -Michigan .• bronze, tible and.-.'lax-carcdiv Tho' hybrids were -all badly rusted,/and; wero intermediato' as to the other, characters. . Thus . susceptibility was _ the. ; " dominantcharacter,-./,and*, im-munity.'.-,'was/ robgwivo.'!/./;'ln, - the, - next.generation ; thero^:wai i pn'o; J)larit f : immune. to rust,' as. against ithreft'' susceptible; and • one ' was. df nse-oared, two intermediate, and' one lix:' Thoiriist-proo.f.'steds of, this'.generationi' would air breed true. '■ ' The /valiio r of ,-tKis MiscoVery• will be ap--parent;,'when-Vwo>efflember •tli&t- in >'dne year th© losses'from this rust disease in Prussia alone Were Wtimatod ;'atr£20.660,000,-or'-'one-. third tho totSl crop. Tho' wbrld's •'• lesses from tho tro, put at over £10(1.000,000 iannuan? ' ■ Efforts to produce blue andalusiah fowls .thdt would breed,..'toie."' failed:- becauso it '.•was ■discovered \ that ./the'-" blub: was- an' intes--'mediate character. -Blacks.' or whites 'colild : b6 mado to breed true,, but not b'vies ~ :In these,dayslwhen-farAiers-,ar6.beginning' •to ; 'consider...whether hybridise; to.um'provo tho qualities' of ''their farm .seeds or. secure iniimunitj': to' certain (diseases, : vthcse .princinles ; ; vwill--', fco ■ useful. ■... ' . /f-; : : .v .r i. •