400 IV- CONKKUK.NCK INTKIIN \TI(iN Ml: liK CKNKTjni K. 



SOS-DOUlII.K-TlIROWt.NG SINGLE TVPI-: KVEIlSr OUTINC SISr.l.K 



Ovules l'olleii Oviilos Pnlli'ii 'iin;itilo lo cèiiy \ ai- V 



Ail XV AH T\ Il — 1 XY Ail .n, 



1 \„ 

 1 -V 

 " - I '.'/ 

 wlicru -1 II piiiii'Ios .-ii-c i-c(|iMi'e<l I" l'sliiliil 

 llie full scrii-s. 

 (Iirspiiii- ail single. OlTspring mixi'd. llic (lniilil(?s Immii- sli(;liily 



In exci'ss. 



Sinr-c in Ihc |i(>ll('ii ni' llic non-iiouijle-llirowint;' single I.n|>(' X jiikI '^' arc 

 linked togeilier, and in Liial of tlic evcrsporling single Jiolli \ and "\ arc 

 absent, \vc are unable to niake llie cross wlierc X and Y are coniriijuted lu Ihc 

 zygote, tlie oneby llic niale and tbe olher Ijy llie female germ; tiiat is lo say \ve 

 are unable in this case to illustrale Ihe converse condition of partial repulsion '. 

 But in tbe case of certain oliicr faclors in Stocks Ibis difficulty does not occur. 

 \\'e find, l'or example, thaï Ibis kind of inler-relalionsbip exists also between 

 tbe factor producing wliite plastid colour (\V) and Ihe l'actors for singleness 

 (X, Y) and again behveen tbe factor W and tbe faclor ]iroducing pali' sap 

 coloiirs (P). 



If a cross is made between a fnrm wilii wiiitc piasiids (W'j ainl une willi 

 rream plastitls (m), (lien, when Ihe mating is in tbe l'orni 



XVW X ■'!/"• 



isinylo wliilci (doiilili' cieain; 



tbe gamelic séries in F, is prol>ably as follows; 



Il — I \V w 

 1 XV w 



■1 .7//\V 

 Il I .11/ tv 



wbereas when Ihe mating is in Ibe i'orm : 



Û w X .' ;/ W 



[single crcniii) 'double wliile; 



XYmi and xijW are Ihe more fréquent, XY\^' and .ri/ w tbe rarer terms in tbe 

 séries. Hère we bave tbe efïecl bolb of partial coupling (in tbe tn-sl of Ibe Iwo 

 malings) and partial repulsion (second mating) between Ihe factor \\ on tbe 

 one band and Ibe linked X'i' couple whicb behaves as a unit, on tbe olbcr. 



Again when a cross is made between Iwo forms, one containing tbe l';ictor 

 for while plastids (W) and also tbe factor producing pale sap colour (P)and one 

 in whicb P and W are bolb absent, mosl of Ibe coloured individuals in Fj are 

 pale wilh wbile plastids or deep coloured wilb cream plastids; few sbow Ibe 

 combinalion of pale sap colour wilb cream piasiids or deep sap colour with 

 wbite plastitls. 



ni' |iarti,'il rr|iiilsi(i 



I XY 



I .,,/ 



I -v. 



