I'l Mendd'uiH I nlierltancc and Ycllutn Ruxf In Wheat 



were graded at the final examination, and these contained "291 individuals 

 with only a slight attack or none, and 893 on which the attack was either 

 moderate, bad, or very severe. These numbers are very close to the 

 3 : 1 Mendelian ratio. Of the other cultures in this group, seven showed 

 much less evidence of segregation, but, as the majority of the plants in 

 each case were much less severely attacked than those of the homozygous 

 susceptible cultures growing alongside, it is probable that these were 

 the offspring of heterozygotes. 



Two other cultures, 1/3 and 38/22, proved to be as resistant as the 

 first 15 given in Table 111. 



Table ^ . Analyaii: of F-j cullitres (191'.)) (jivwujrom F<, plants which had 

 a slight attack of rust in 1918. 



Extent of the rust attack at filial cxamiiiation 

 Plants (28th July to 1 1th August) 



OiJture in * , 



No. culture None Trace Slight Moderate Bad Very severe 



2/8 52 12 — 9 20 8 3 



7/15 48 II — 9 5 12 1 



9/3 7(t 15 — 22 28 4 1 



11/3 51 11 — 7 26 5 2 



07/10 54 12 — 6 10 11 15 



67/11 73 n 3 12 24 8 15 



13/13 lit 21 9 9 8 2 



39/7 87 — — 15 48 14 10 



41/16 48 — — 8 28 6 6 



52/13 48 — — 8 24 10 fi 



52/23 67 _ _ 13 31 17 6 



56/14 65 — — 20 21 l> IS 



72/2 44 — — 5 13 7 19 



72/12 50 — — 3 15 12 20 



9/18 29 — — 7 12 9 1 



10/9 49 _ _ 5 23 15 6 



17/13 66 — — 20 42 4 



17/24 62 — — 10 43 7 2 



22/1 48 — — 2 30 16 



23/17 50 — — 3 21 25 1 



24/15 31 — — 1 10 IS 2 



8/5 43 — — 1 2S 10 4 



30/11 (63) 



32/16 (34) 



33/23 (44) 



38/6 (32) 



Totals: 1184 93 3 195 511 238 144 



[22 cultures] ' ^^ — — ' "^ v ' 



291 893 



(e) Si.xty-threc cultures were raised from F^ plants which had been 

 moderately attacked. Fourteen of these proved to be homozygous 

 susceptibles, for every plant in these I 1 cultures (791 plants in all) was 

 either badly or very severely iiisted. 



