SMUT EXPERniENTS IX VICTORIA. 595 



fact that in many cases the secondary ears or later growths may 

 develop disease, wliile the more advanced ears of the same plants are 

 free. 



Amonj; the numerous varieties grown there were several which 

 promised to be more or less bunt-resistmg, and these were used as 

 parents for further crosses, but the only one found to be absolutely 

 free this season, after the most thorough infection of the seed, was 

 Medeah. Various selections and unfixed crosses are also being tested, 

 and, naturally, those containing IMedeah blood receive special atten- 

 tion. 



Out of numerous selections from various crosses, only two were 

 found to be clean after infection, apart from those containing Medeah, 

 and of those with an admixture of Medeah blood, there were also two. 

 Tlie crosses, together with the number of selections found to be bunt- 

 resisting this season are as follow : — 



Egyptian x Tardent's Blue — 4 Selections. 

 Blue Heron 



Tripol i - 1 „ £■ 



Tardent's Blue ?^<._ 



Bobs X Medeah ... — 7 



TripoU 



Bobs -G 



Medeah 



These will be tested in a similar fashion to Elorence and Genoa during 

 the coming season. 



The difficulty and uncertainty here lies in making sure that the 

 bunt-free plants owe their resistance to constitutional characters and 

 not to the accident of the spores failing to germinate or the mycelium 

 of the fungus inside the plant being unable to reach the ovary. The 

 question as to the hereditary character of bunt-resistance can only 

 be definitely settled by growing the seed from such bunt-resisting 

 plants for several seasons in succession, after being thoroughly dusted, 

 witli spores, and proving that immunity is or is not an inherent 

 characteristic. Once an immune parent is obtained, then the desir- 

 able qualities to be associated with this immunity can be produced 

 b}' further crossing. 



There are thus at least two methods of procedure in seeking to 

 obtain a variety of wheat immune to bunt ; either to start from what 

 is known as natural immunity, in which the plant from its very 

 constitution inherits a certain amount of resistance, as in the case 

 of Medeah, or by means of selection to arrive at a plant which has 

 acquired this character, as in the supposed case of Florence. 



It was the idea of the late Mr. Farrer to inoculate the seed which 

 produced the variable generation of his new crosses with bunt 

 spores, and then select bunt-free plants from the new generation, 

 tliereby hoping to secure an imnuine strain or one at least less suscep- 

 tible than tlie parents. But in either case it has yet to be proved that 

 imnuuiity is absolute and complete, and that rich feeding or starva- 

 tion, for instance, or the severity of the infection, may not break 

 down the power of resistance. 



