July is, 1914 
Fusarium on Sweet Potato 
275 
Nectria Goroshankiniana Wahrlich (1886): 
Perithecia, 360 by 320^, 1 ascospores, 12 to 15 by 4 to 5/1; conidia (subnormal), 
20 to 30 by 3.3 to 4.4/1; chlamydospores described, but their connection with 
the perfect form unproved. 
Nectria coffeico la Zimm. (1901): 
Perithecia, 300 to 400/*; ascospores, 10.5 to 13.5//; 3- to 5-septate conidia, 40 
to 50 by 5/i, chlamydospores (?) 
Hypomyces ipomoeae (Hals.) (1892) Wollenw. (1913c): 
Perithecia, 200 to 425 by 150 to 350/f (absolute fluctuation); ascospores, 8 to 
16 by 3 to Sfi (absolute fluctuation), 3- to 5-septate conidia, 30 to 70 by 3.75 to 
5.5/i (average fluctuation); chlamydospores, 7 to 10/c. 
Nectria cancri Rutg. (1913): 
Perithecia, 400 to 500 by 300 to 400/t; ascospores, 10 to 13 by 3 to 5/t; 3- to 
5-septate conidia, 30 to 60 by 3 to 5/i; chlamydospores (?) 
The illustrations of these fungi agree closely in the general appearance, 
but in the size of perithecia, ascospores, and conidia differences are 
observed. Some of these may be due to the special condition under 
which the fungus was collected or grown; others may be constant. The 
fact that fungi looking alike at the first glance will be proved different in 
pure culture became evident to the writer when he found on the taproot 
of Cannabis sativa a fungus with perithecia resembling those of Hypo¬ 
myces ipomoeae . When this organism was studied in pure culture for a 
year, measurements of all spore stages were made. As is seen in the 
diagnosis, this hemp fungus developed larger perithecia and ascospores 
than H . ipomoeae . Its conidia, however, were never predominantly 
5-septate, while in H . ipomoeae as many as 100 per cent of them can be 
found. The perithecia appeared slowly in the hemp fungus 20 to 30 
days after the culture was started, while H . ipomoeae required only 10 
to 15 days. Attempts to reduce these differences in size (PI. XV, figs. 
A, B , and C), septation (PI. XIII, figs. G and /), and rapidity of growth 
failed. One fungus could not be transformed into the other, although 
their relationship seems to be beyond question. 
Since Nectria cancri has the size of the hemp perithecia and the normal 
mature ascospores illustrated by Rutgers are broader than his diagnosis 
(iQ to 13 by 3 to 5/*) gives, the hemp fungus may be provisionally deter¬ 
mined as Hypomyces cancri (Rutg.), n. comb. ( = Nectria cancri Rutg.). 
The fact that chlamydospores are not mentioned by Rutgers does not 
detract from this conclusion. The writer grows chlamydospores by over¬ 
watering the culture, but this method may not yet be well known. • 
The remarkable variation in the shape of the neck is illustrated in Plate 
XV, figs. B and C, and reminds us of Nectria moschata Gluck. Plate XV, 
fig. B, shows two perithecia with a stromatic base, which is lacking in the 
other illustrations. 
1 Measurements of the size lacking in the diagnosis have been derived approximately from illustrated 
perithecia. 
