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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



crosses the tube and prevents retreat. One, two, or more additional 

 divisions of the apical cell take place, and from the side of each of 

 these newly constituted cells buds or processes appear, which gradually 

 enlarge, and in time are converted into secondary spores, or promycelial 

 spores, into which some of the contents of the old spore pass, and these 

 smaller bodies are eligible for the production of mycelium, which is pre- 

 pared to tind an entrance into the leaf of some young and new host plant, 

 and producing infection commence the cycle over again (fig. 2). Thus, 

 then, we have in order of succession spermogonia, a?cidiospores, uredo- 

 spores, and teleutospores, each of the three latter capable of producing 

 secondary spores, but the last of all producing the promycelial spores 

 which are the medium of reinfection, from the complete and perfect 

 condition of the Puccinia. 



It may be mentioned, in passing, that the life-history in the genus 

 Uromyces, where the teleutospores are only one-celled, is precisely 

 similar. 



But all these stages are not always to be found associated together. 

 The chain is not always perfect. In some cases the Mcidium only is 



Fig. 2. — Telectospore germinating. 



known, with or without spermogonia; or in other cases only the uredo- 

 spores are known ; or in certain cases only the teleutospores. In each 

 of these instances the fungi are regarded as imperfect, or, at least, as 

 imperfectly known Uredines. 



Besides these cases, in which a^cidiospores, uredospores, and teleuto- 

 spores are produced on the same species of host-plant, there is another 

 group which those who have implicit faith in heteroecism contend 

 produce the eoidiospores with spermogonia on one species of plant, and 

 tie uredospores and teleutospores on another and quite different species 

 of host-plant. Let each be persuaded in his own mind, as it will serve 

 no '4o.)«l purpose to enter upon discussion here. 



'I here is another vrroup in which only the spermogonia, uredospores, 

 and teleutospores are known, and these all occur on the same host-plant. 

 Here tlx lecidiospores are absent. 



In a fourth group only the jecidiospores and teleutospores are known, 

 and those occur upon the same species of host-plant. The uredospores 

 are wanting or do not produce pustules of their own. 



