M. C. COOKE, NOTES ON PODISOMA. 2G3 



structure is the same. In fact we are not alone in this opinion, 

 as Bonorden includes Gymnosporangium juniperi (Fi\), the only 

 described species, under Podisoma, as Podisoma gymnosporangium* 

 It will be seen that Podisoma foliicolum of Berkeley is very much 

 further removed from Podisoma than Podisoma from Gymnospor- 

 angium. In fact, it is not a very near ally of either. For the pre- 

 sent we shall continue to speak of Gymnosporangium juniperi under 

 its usually accepted name. The normal form occurs in the United 

 States as well as in Great Britain, but recently Mr. C. H. Peck 

 has sent us from Albany, N. Y., a variety upon the common cedar 

 (Juniperus Virginiana) , which is smaller in its external develop- 

 ment, so far as our specimens go, but with marked difference in 

 structure. The hyaline peduncles of the protospores are thicker 

 than in the typical form at their smallest diameter, and these ex- 

 pand upwards until they attain very nearly the diameter of the pro- 

 tospores, reaching which they are constricted deeply, so that the 

 peduncles are most conspicuously clavate (pi. xviii., fig. 3). The 

 protospores are rather more brightly coloured, nearly the same in 

 size, but rounded above, so that each cell is less triangular than in 

 the typical form. This is at least a well-marked variety, and as 

 such we have called it, variety clavipes. A better acquaintance 

 with its ultimate development, and specially of its teleutospores, 

 is essential before determining its claims to be considered specifically 

 distinct. 



Of Podisoma three good species are recognized. The Podisoma 

 Juniperi-communis of Fries, with very long protospores (pi. xix., 

 fig. 1). The Podisoma fuscum of Cordaf, which is also the 

 Podisoma Juniperi-sabino3 of Fries, with short protospores (pi. xix., 

 fig. 2), and the Podisoma macropusoi Schweinitz, with protospores 

 of a length intermediate between the other two (pi. xix., fig. 3). 

 Corda was manifestly wrong in referring Podisoma Juniperi com- 

 munis of Fries as a synonym of his Podisoma fuscum. 



Podisoma juniperi is very common on the juniper {Juniperus 

 communis) in Britain in the spring. The branches on which it 

 occurs are swollen at the infected spot to nearly double their normal 

 size, and the orange tremelloid masses of the fungus are protruded 

 through orifices of the bark like spines. As winter approaches all 

 external manifestations, except the gouty swellings, disappear, and 



* Bornorden, Handbuch der Allgem : Mykologie (1851), pp. 148. 

 t Corda, Icones Fungorum, vol. hi., p. 36, t. vi., fig. 93. 



