Parasitism and Imnutnity. 



Table II. — Selections from Crosses, with percextage of Bunt- 

 coniinuad. 



S2, 



Several of the crosses turned out bunt-free, particularly those into which 

 Mecleah enters, and it only remains to be seen after further trial if this is a 

 hereditary quality. They will be tested in a similar fashion to Florence and 

 Genoa. 



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 in- 

 side the plant being unable to reach the ovary. I have had numerous exam- 

 ples in different seasons of ears being only partially smutted and the reasonable 

 explanation is that from the nature of the season and the consequent growth, 

 the mycelium had not sufficient vigour, or was not sufficiently nourished in 

 the straAv to produce spore-formiiig hyphae in every grain. The clean grains 

 were taken from such partially-smutted ears and sown again after proper 

 inoculation, when it was found that they were liable to infection, thus proving 

 that there was nothing in the grain itself which caused it to escape. The ques- 

 tion as to the hereditary character of the bunt-resistance can only be definitely 

 settled by growing the seed from such bunt-resisting plants, for several sea- 

 sons in succession, after being thoroughly dusted with spores and proving 

 that immunity is or is not an inherent characteristic. Once an immune parent 

 is obtained, then the desirable qualities to be associated with this imnuinity 

 can be produced by further crossing. Attention has hitherto been so exclu- 

 sively devoted to providing remedies for smut, that the attempt to produce 

 smut-resisting plants is well wortlw of being persevered with, and the experi- 

 ments so far carried out are decidedly encouraging. 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 ac- 

 quired this character, as in the supposed case of Florence. It was the idea of 

 the late Mr. Farrerto inoculate the seed which produced the variable generation 



