17 



Gambier, chiefly on rich, loose, black soil with much lime, 

 limestone forming the subsoil, but very little could be noticed 

 on sand. What is most notable is that a variety of wheat, 

 called " creeping wheat," distinguished by very stiff, glassy, 

 upright stalks, appeared to be much less affected, if at all, than 

 any other kind. It also was the latest in ripening. These facts 

 probably point an important moral. 



In 1871-2 rust prevailed much in Monarto, chiefly on the 

 best loamy or clayey soils with limestone or clay subsoil, while 

 splendid grain was obtained on patches of very sandy soil, 

 ploughed and sown hurriedly for want of time. 



At New Mecklenburg wheat was found as rusty as elsewhere 

 near a salt creek, the soil being surcharged with saline ingre- 

 dients. At Ardrossan, Yorke's Peninsula, all the crops were 

 much affected with rust in the past season, and no difference 

 was observable between those bordering the seashore and those 

 some miles inland. The soil is abundantly supplied with salt 

 and lime. 



The above observations are intended to show that rust occurs 

 equally on all soils, and under very varied circumstances 

 respecting locality and situation. They seem to prove that the 

 occurrence of the fungus does not depend either on the soil or 

 local circumstances, but more likely upon — (a) Particular 

 atmospheric conditions, (b) The structure of the wheat-plant. 

 (c) The constitution of the soil (that is the soluble salts it 

 contains) ; and suggest the direction in which the remedies lie. 



In respect of the first the power of man is inefficient to do 

 much, except in so far as by planting forest trees extensively 

 (say a strip around each field) he can, to a considerable extent, 

 regulate the moisture in the soil, as they promote the infiltra- 

 tion and retention of the rainwater, and protect the land from 

 injurious winds. 



The structure of the plant and the constitution of the soil 

 are much more in the power of man. What promises by far 

 the best results is the production of a wheat plant combining 

 a hard smooth stalk and a full fine grain. This will 

 depend on the ingredients of the soil, the constitution of 

 which is inevitably changed for the worse by cropping year 

 after year, without returning to the soil in a suitable form the 

 ingredients removed by the crops. To determine these is the 

 province of the agricultural chemist. Wheat and all other 

 grain crops require a great number of substances for the pro- 

 duction of seeds ; the absence or insufficiency of any one of 

 them will cause weakness and sickening of the plant, expose it 

 to the invidious attacks of its enemies, and ultimate decay and 

 death. Por the building iip of the stalks, leaves, and husks 

 soluble silicates besides the carbon (derived chiefly from the 



