BIOLOGIC SPECIALIZATION IN THE GENUS SEPTORIA 
17 
**In forma Conv. arvensis observavi sporulas 35-50x1-1.5, aciculares 
minutissime 5-6 guttulatas v. septulatas hyalinas; in forma Calystegiae 
sporulas 35-40x1-1.5, continuas, hyalinas utrinque obtusiusculas. An 
differentiae constantes?" (Saccardo, Sylloge Fungorum, 3- 536.) 
The forms of Septoria collected at Urbana upon Convolvulus arvensis 
and C, septum fitted respectively the characterizations of the above-named 
forms as quoted. One hundred spores from C. arvensis had an average 
spore length of 44 microns, whereas a like number of spores from C. sepium 
averaged only 35.5 microns. There was a difference in average spore 
length whatever the conditions under which the two forms were compared. 
The distinctions mentioned regarding spore tips is not evident, but the 
spores from C. arvensis were always the more definitely septate. With 
respect to host characters there is little by which the forms can be dis- 
tinguished. 
The results of the infection experiments (tables 2 and 3) proved that 
the forms of Septoria from these two bindweeds are likewise distinct in 
Table 2 
Infections with Septoria septulata sp. nov. from Convolvulus arvensis 
Conditions 
Plants Inoculated 
No. Leaves 
Infected and; 
Inoculated t 
No. of 
Spots 
Remarks 
g-b3 
g-b 3 
g-b3 
g-b o 
g-b 3 
g-b 3 
g-b 4 
g-b 3 
g-b 3 
g-b 3 
g-b 3 
g-b 4 
g-b 4 
Convolvulus arvensis . 
Convolvulus sepium 
(I <( 
Ipomoea purpurea. 
Ipomoea batatas. . . 
Ipomoea learii .... 
Ipomoea setosa. . . . 
15/20 
4/5 
20/20 
many 
<( 
39/45 
3/20 
3/3 
2/7 
1/9 
II 
12 
5 
I 
9/39 
29 
0/5 
o/io 
0/15 
o/io 
0/7 
0/17 
o/io 
0/4 
Check, most of the leaves 
killed 
Pycnidia and spores but 
spots very small 
their pov\^ers of infection, for each can cause vigorous infection only upon 
its original host. The fungus from C. arvensis does infect C. sepium to 
some degree, with 9 out of 39 leaves inoculated showing a few small disease 
spots, but this is to be compared with 39 out of 45 leaves upon the original 
host, on which the spots were ordinarily so numerous and so spreading that 
the leaves were entirely killed. When C. arvensis was inoculated with the 
