CANKER OF SCOTS PINE CAUSED BY DASYSCYPHA SUBTILISSIMA. 187 



We desire to thank Messrs J. Murray and Mowat who have 

 kindly forwarded specimens of the fungus. 



Explanation of Plate. 



Fig. I. Photograph of stem of Pinus sylvestris showing cankered area and 



fructifications of Dasyscypha siibtilissima, Cke., about half natural 



size. 

 ,, 2. Photograph of side view of specimen seen in Fig. i about half 



natural size. 

 ,, 3. Photograph of part of cankered area showing {a) ascigerous and {b) 



conidial fructifications of Z)aj-^'jry/^a«/(5^i7?.rj-/wa, Cke. ( x about 3). 

 , , 4. Ascus of Dasyscypha subttltssitna, Cke. ( x 400). 

 ,, 5. hscns of Dasyscypha Willkominii, Hartig ( x 400). 

 ,, 6. Median longitudinal section of conidial fructification of Dasyscypha 



stibtilissima, Cke. ( x 28). 

 ,, 7. Conidiophoresand conidia of Z)(zyj(ry/.^rt: jz<(5/i7mmrt, Cke. ( x about 



1 100). 



31. The Two Rust Diseases of the Spruce.^ 



{With Plate.) 



By A. W. BORTHWICK, D.Sc, Advisory Officer for Forestry to the Board 

 of Agriculture for Scotland, and Malcolm Wilson, D.Sc, F. L. S., 

 Lecturer in Mycology in the University of Edinburgh. 



Chrysomyxa Rhododendri, De Bary. The Spruce Blister 

 Rust, Rust of Rhododendrons. 



Chrysomyxa Rhododendri was first recorded in Britain by 

 D. A. Boyd in June 1913, who discovered the uredospore and 

 teleutospore stages on Rhododendron hirsutum at Douglas Castle, 

 Lanarkshire. 



Shortly afterwards, in October 1913, material of the aecidial 

 stage of the fungus on Picea excelsa was sent for identification to 

 one of the writers from the south-west of Scotland, and its 

 discovery was recorded in the Proceedings of the Botanical 

 Society of Edinburgh in June 1914.- 



The life-history of this species was first described in 1879 by 

 De Bary,3 who showed that the forms previously known as 

 Aecidium abietinum and Uredo Rhododendri were stages in the 



^ Reprinted from Notes of the Royal Botanic Garden, No. xli., 1915. 

 ^ Proc. Bot. Soc. Edinburgh, vol. xxvi., p. xxxiii., 191 3-14. 

 '^ Bot. Zeit., Bd. xxxvii., p. 761, 1879. 



