8. F. Armstron« 6i> 



((J) Re.'iidls obtained from (he t\ cidtures (191'J). 



(a) General. Tlie spring drought proved a very severe test, for all 

 the cultures, and some ol them, which were on rather poorer ground, 

 had to be abandoned. Ample material was provided by the remaining 

 170 cultures which contained some 8500 plants. These cultures were 

 examined in regular order, and the first appearance of rust on each noted. 

 Immediately an attack was observ^ed, all the plants were numbered, and 

 the rusted ones indicated in a book. The cultures were repeatedly ex- 

 amined, from the first week in May until the end of .luly or later, to 

 see to what extent the attack had spread. At. the last examination the 

 intensity of attack on each plant was noted as in 1918. 



The conditions under which the plants were grown proved so favour- 

 able to rust attack tliat. almost without exception, the cultui'es were 

 more severely rusted than their F^ parents Jiad been in the jjrevious year. 

 This is indicated to some extent by the results given in Tables III to VII. 

 Cultures raised from badly rusted F., plants were still more severely 

 attacked in 1919. It wiU be seen also that, in the 69 cultures which gave 

 evidence of segregation, very few plants actually remained rust-free. 



Table III. Results of analt/sis of the F^ cultures (1919) 

 grown f 7-0 in rust-free F.2 plants. 



Extent of the rust attack at final e.vaniination 

 Plants (28th July to 11th August) 



{b) Cultures raised from rust-free F^ plants. Seventeen of these cultures 

 were grown, but in only two of theni did every plant remain absolutely 

 free from attack. Of these seventeen cultures, the first ten in Table III 



