THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL, 



Vol. XVIII. DECEMBER, 1897. No. 12. 



Parasitic Leaf-Fungi. 



By Rkv. ALEX. S. WILSON. 



About the time when the blackberries are ripe, after a 

 short search one can generally find a bush the leaves of 

 which have a paler appearance than ordinary ; closer 

 inspection shows the under surfaces of the leaves flecked 

 here and there as if with sjiecks of soot. With the aid 

 of a pocket lens eacli speck is seen to L'onsist of tufts of 

 little club-shaped bodies, and if we scrape .some off, mount 

 them on a slide, and place it under the microscope, we see 

 that they are cylindrical cells, each made up of from 

 three to ei«^ht joints, and supported by a short stalk. 

 Their form is so characteristic that, once seen, there is 

 no difficulty in recognizing it again. These are the telu- 

 tospores of the bramble brand (Phragmidium violaceum), 

 a parasitic fungus belonging to the order ^cidiomycetes 

 (or Uredines), all of which inhabit living plants. 



The leaves of various species of mint are in autumn 

 often (lotted over in like ni;inner wnth dark-colored spots, 

 due in this case to the teluto&jtores of Pucciuia mentha*, 

 each composed of two joints of hemispherical form. By 

 this two-celled chjiracter the Puccinia genus is distin- 

 guished from Phragmidiuni, which has telutospores 

 usually consisting of more than three joints. On the 

 meadow-sweet a brand, Triphragmidium ulmaria^ occurs, 

 having three-celled telutospores ; those of the brands 



