-j^^^ . BOARD OF AGRICULTURE. 



will have no effect whatever. Parasitic floweiiess plants, like the 

 entozoa, treated of in Prof. Brackett's lecture, are restricted in their 

 powers of attack, being able to live on certain species only, and 

 even on particular parts only of particular individuals of these 

 species. It is my own belief, based upon a careful study of the 

 literature of the subject, that the spores of the species of Uredo, 

 and of Puccinia (if we consider that a distinct plant) must migrate 

 from a diseased grain to a plant of barberry, there to undergo a 

 transformation analogous to changes in animals, spoken of by 

 the lecturer upon animal parasites. The fungus of the barberry is 

 ^cidium, and this appears to be a fully ripened form of the 

 mildew fungus, ready to recommence its ravages. 



linger, a Vienna botanist, thinks that the rust and mildew are 

 cases of vegetable exanthemata. Exanthematous diseases are 

 those which belong to the group of measles and allied afiections ; 

 and Unger advances the hypothesis, based upon his observations, 

 that these fungous diseases of plants are closely connected with 

 if not identical with these exanthematous diseases of man. These 

 views have of late received unexpected confirmation from the 

 independent experiments of Dr. Salisbury and Dr. Jules Lemair. 

 Dr. Salisbury has obtained from malarial districts in Ohio, speci- 

 mens of the fungus which produces miasm. He caught some of 

 the spores of the malarial fungus upon glass, and transferred the 

 spores to a district where malaria was unknown, and the disease 

 termed fever and ague was produced. Dr. Lemair has proved that 

 these spores exist in Europe, and produce the same disease there. 

 Dr. Salisbury also shows that many other diseases are caused by 

 fungi, one in particular being produced by the fungus of mildewed 

 straw. This disease is inoculable, and it closely resembles the 

 measles. 



Dr. Muecke is of the opinion that the rust of wheat is an effect 

 not the cause, or at least a second not a first cause, being itself 

 superinduced by the corrupted state of the juices of the plant. 

 Ho says that where the rust destroys we may safely infer that the 

 plants were in a suffering state before they were attacked. The 

 red rust, he says, has not destroyed the crops of South Australia, 

 it has merely furnished the eruption thereto. But on the other 

 hand, it is equally true that on vast surfaces the red rust has been 

 the main cause of the destruction of plants in regard to the for- 

 mation of grain. He gives the following proof of his theory. 

 Part of a field of wheat in which wild oats had prevented the 



