52 THE VICTORIAN NATURALIST. 



account of the position originally assigned to it. It also illustrates 

 the necessity for having plenty of material before coming to a 

 final decision as to the nature of some rusts, so that the different 

 forms entering into its life-history may be secured, if possible. 

 This species was first found in New South Wales in November, 

 i860, and was named by Berkeley Roestelia polita. It may be 

 explained that Roestelia is the name given to an aecidium when 

 the cup is elongated and hornlike, and this particular form is 

 confined to the Rosacese. It was very peculiar, to say the least 

 of it, that this form-genus, which is only known elsewhere on the 

 Rosacea, should occur here on the Polygonacese. So I impressed 

 on my fellow-member, Mr. C. French, jun., the desirability of 

 carefully examining M. cunningharni for rust whenever he 

 should happen to come across it. Just 45 years after the original 

 specimens were collected, in the same month — November — he 

 found the rust, and in forwarding it to me stated that after nearly 

 a day's hunt, and examining hundreds of specimens, only one 

 plant was found with the rust upon it, at least readily visible to 

 the naked eye. On examining these specimens the complete 

 stage was found, the Roestelia nature of it was disproved, and it 

 is now placed in its proper position as Uromyces politus, along 

 with Uromyces polygoni found on Polygonum. 



Time does not permit of touching upon a number of important 

 questions suggested by the consideration of the rusts, such as the 

 origin of parasitism, the specialization of parasitism, predisposition 

 or the tendency to disease exhibited by an organism when the 

 conditions are favourable to the development of the parasite, 

 immunity, and other phenomena. I may again refer to the 

 evident advantage of taking up special groups of organisms, and 

 bringing them up to date, so that in any future research in that 

 direction it may be known definitely what was the state of our 

 knowledge at a given period, and knowing what has been 

 accomplished this may stimulate to further effort in extending 

 and increasing that knowledge. And I trust that this rapid and 

 rather sketchy survey of the rusts of Australia may induce some 

 of my hearers to pick up the first rust they meet with in their 

 rambles and examine it, and that others who are Micawber-like 

 waiting for something to turn up in the way of a microscopic 

 hobby, may here and now decide to take up the study of these 

 fascinating histories which lie concealed under the guise of a 

 cluster-cup on the Marigold or the rusty-red powder on the stem 

 and leaves of a wheat plant. 



Some excellent illustrations of the new Australian hall at the 

 National Museum, Melbourne, appeared in the Weekly Times of 

 Saturday, 26lh May, 1906. 



