DISEASES OF PLANTS. 145 



wheat from growing, was cut for hay. Immediately the wheat 

 sprung up healthy and vigorous and developed full ears and fully 

 grown grains ; not a particle of rust was perceptible on these 

 parts of the field, whilst the surrounding thick and high wheat was 

 completely covered with it. The cause assigned is, that the wheat 

 in one instance did not grow till the time was passed in which the 

 influences supervened that pre-disposed the plants ; consequently 

 they became strong and healthy. While the red rust spores passed 

 over them they were not infected, because the spores did not find 

 the conditions of their existence, that is diseased sap and weak 

 cells upon them. This is clear .enough ; because surrounded as 

 these mown spots must have been by the wheat on which the rust 

 prevailed, the former could not have escaped if the same conditions 

 had prevailed in them as in the other. The following tabulated 

 results will show how contradictory are the opinions held by differ- 

 ent members of the South Australian Commission : 

 Eed rust is caused, say some, 



1. By the exhaustion of the soil. 



2. By late sowing. 



3. By manuring. 



4. White straw is the best. 

 These results are very contradictory. 



Ergot is a diseased state of grain in which the unimpregnated 

 seed or grain takes on the form of a spur. "Ergot consists of a 

 very dense tissue formed by polygonal cells united intimately with 

 one another and filled with an oily fluid." Ergot attacks rye' prin- 

 cipally, and this diseased grain is used sparingly by physicians 

 in certain diseases coming under their care. When this diseased 

 grain is used with common rye as an article of food, it produces 

 most terrible maladies in domestic animals and man. In the case 

 of a duck which was forcibly fed with flour mixed with the powder 

 of ergot, forming a seventeenth portion of the whole compound, 

 drops of blackish blood oozed from its nostrils at the end of five 

 days ; the beak soon afterwards changed color, and the tongue 

 rotted at the extremity ; the animal died in ten days, after having 

 taken altogether one ounce and seven grains of ergot. Other 

 experiments equally striking have been made, and their results are 

 such as to cause us all to join in the wish expressed by Professor 

 Henslow, that they may never be repeated. But the importance 

 and propriety of making them once will be readily admitted when 

 it is known that they were undertaken expressly to test the 

 10 



Red rust also prevails : 



1. On newly cultivated lands. 



2. By early sowing. 



3. Manure prevented it. 



4. Purple straw is the best. 



