SOME ACCOUNT OF POLYSTIGMA rvUBRUM. 329 



pi. XXV, fig. 1, sec. Saccard. (1821) — Sclmra., ' Flor. Saell./ 

 ii, 179 (1803). 



Sphseria rubra, Fries, ' Obs. Myc.,' i, 172 (1815) — Kunz. 

 et Schra., ' Myk./ Heft ii, 2^ (1823)— Wallroth, * Flor. Cr./ 

 ii, 847 (1833)— Link, ' Handb.,' iii, 365 (1833). 



Sphseria hyetospilus, Martius (pro parte), 'Fl. Crypt. 

 Erlaug.,' p. 478 (1817)-Fr. Nees, ^ Nov. Act. Ac. L.-C. Nat. 

 Cur.,^ ix, 253, pi. vi, fig. 21 (1818). 



Dothidea rubra, Fries, ' Syst. Myc./ii, 553 (1823) ; ' Sum. 

 Veg. Sc./ p. 387 (1849); exs. No.* 191— Berk., 'Eng. Fl.,' 

 p. 286 (1836) ; 'Outlines Brit. Fung.,' p. 391 (1860). 



Ascochytse sp., Libert, 'An. Sc. Nat.,' Ser. 2, vii, 124 

 (1837). 



Septoria rubra, Desmaz., ' PI. Crypt. Gall.,' Ed. 2, xv, 

 No. 734 (1843) ; ' An. Sc. Nat.,' Ser. 2, xix, 342 (1843), var. 

 /3. amygdali. 



Libertella sp. (rubra), Bonord., ' Handb. Mykol.,' p. 55, 

 (1851). 



Recorded from England, Wales, Scotland, France, Ger- 

 many, Italy, America, &c. 



This fungus-parasite on species of Prunus does not appear 

 to have been so injurious in this country as on the Continent, 

 where it has in certain places, as at Berlin, committed great 

 ravages in fruit orchards. It usually makes its appearance a 

 little before midsummer as yellow, afterwards red, spots on 

 the leaves of Prunus domestic a, P. spinosa, P. insititia, 

 and has also been recorded (at least, in the spermogone stage) 

 on Amygdalus. These spots, which are more or less orbicular, 

 and often confluent, from |^th to f ths of an inch in diameter, 

 are developed on both surfaces of the leaf, but more particu- 

 larl}'' on the lower ; they consist of the abundant mycelium of 

 the fungus closely compacted with the hypertrophicd mesophvll 

 of the leaf, which thereby becomes somewhat thickened, and 

 of a fleshy consistence. The chlorophyll of the attacked cells 

 is destroyed, and the mixed tissue or stroma assumes the 

 characteristic fiery hue, which reminds one, as all authors who 

 touch upon the subject have noticed, of the early stage of an 



