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of the Pine is different again. In any case there is an excellent 

 and neat little problem to be solved in these alleged connections 

 between various forms of Melamjjsora and CcBoma, and I 

 recommend it to the attention of mycologists. 



But of all the fungus diseases which affect Pines, none is 

 more interesting, and few more disastrous, than the one induced by 

 a form long known as Periclermium, and of which P. Pini is the 

 best known. This makes its appearance on various Pines as 

 bladder-hke bags of spores protruding from the leaves or cortex, 

 and springing from a mycelium which destroys the cell-tissues, 

 and which may kill the upper parts of the tree by ringing its 

 stem or branches. 



As long ago as 1874, Wolff* showed that the form referred 

 to is merely the secidium stage of a uredinous fungus found on 

 the leaves of certain species of Senecio, and known as Coleo- 

 sporium. Further investigations partly confirmed and partly 

 contradicted this conclusion, and led to the separation of the 

 Peridemiium which invades the cortex and branches of the 

 Pines {e.g., P. silvestris, P. Strobus, P. Laricio, P. montana, &c.) 

 from the one which infests the leaves of various species of 

 Pinus. 



Cornut especially, in 1886, repeated Wolff's experiments, and 

 found that the cortical form of Peridermium is the jecidial stage 

 of a totally different Uredine [Cronartium) on certain AsclepiadeEe. 



The whole subject of the autonomy of these fungi has been 

 taken up quite recently by Klebahn,J and his investigations lead 

 to somewhat startlmg results. These are too lengthy to describe 

 in detail here, but the gist of the matter may be put as follows. 



The Peridermium (or J^cidium) Pini of authors comprises at 

 least three, and perhaps four, distinct species : — 



(1) P. oblongisporium (Fuckl.) on the leaves of Pinus 

 sylvestris and P. austriaca, the £ecidial stage of Coleosj^orium 

 Senecionis (Pers.). 



(2) P. Cornui (Rostr. et Kleb.) on the cortex of the Scotch 

 Pine, and which is the tecidial stage of Cronartium Asclcinadeum 

 (Willd.). 



* "Bot. Zeitimg," 1874. 



t " Comptes Eendus," 1886, pp. 930-932. 



X "Ber. d. deutsch. bot. Gesellsch.," B. viii., 1890 (Gen.-Versamml. 

 Heft), pp. 59-70. 



