196 BOTANICAL GAZETTE [MARCH 
1G. 3.—Elm leaf, showing one type of Guomonia spot; note absence of 
border of dead or browned tissue and that stromata tend to coalesce. 
Fic. 4.—Elm leaf, showing another type of spot; black stromata sur- 
rounded by border of light brown dead tissue. 
Fic. 5.—Same as fig. 4 except that epidermis covering stromata has begun 
to wear away, giving spot a lighter, somewhat ashen, appearance. 
PLATE IX 
Fic. 6.—Leaf of English elm, showing leaf spot caused by Systremma 
Ulmi; note that each spot is but a single stroma, much more definite in out- 
line than that caused by coalesced stromata of Gnomonia ulmea, and that they 
are raised much more above surface of leaf; note: also wrinkled or papillate 
appearance of stroma. 
Fic. 7.—Schweinitzian type specimen of Gnomonia ulmea. 
Fic. 8.—Perithecium of Gnuomonia ulmea at earliest stage in development 
of beak and ostiole; dark portion of perithecium represents young asci just 
yaa development; note psuedoparenchymatous contents of perithecium. 
m leaf, showing spots caused by Glocosporium ulmicolum, 
sp. noy.; note manner in which spots follow the veins; compare with figs. 3, 
4 als ind 12 for differences from spot caused by Gnomonia ulmea 
Fic. 1o.— Section through stroma of Systremma Ulmi, gubepidecinal in 
origin; note absence of perithecial walls, and a asci are borne in locules 
in stroma which open on upper side of leaf. 
Fic. 11.—Single spot, fig. 124, enlarged 10 diameters, showing isolated 
character of stromata of Gnomo 
IG. 12.+Elm leaf, nates stromata of Gnomonia ulmea as they some- 
times appear, widely separated in spot and somewhat concentrically arranged. 
Fic. 13.— Very young stage in development of perithecium of Gnomonia 
ulmea, showing pyriform shape at this stage, and connection with stroma. 
PLATE X 
Fic. 14.—Acervulus of conidial stage, Gloeosporium ulmeum, sp. nov., 
formed above young perithecium of ascigerous stage, Gnomonia ulmea 
Fic. 15.—Spores of Gloeosporium ulmeum 
Fic. 16.— Very young ange in development of Gnomonia ulmea: a, sheath- 
ing hypha; 6, ascogonium; c¢, ‘‘suspensor” or “infection thread”; d, vegeta- 
tive hyphae which break through stroma to outer surface. 
Frc. 17.—Spores of Gloeosporium ulmicolum. 
Fic. 18.—Single acervulus of Gloeosporium stage of Gnomonia ulmea, 
showing manner of cracking to allow dispersal of spores; hyphae about acer- 
vulus are those of basal stroma as viewed from above. 
Fic. 19.—Ascus and ascospores of Gnomonia ulmea. 
Fic. 20.—Germinating spores of Gnomonia ulmea. 
