The Cottony Leak of Cucumbers 
1037 
for the sporangia of Pythium, and 
the development of an evacuation tube 
from the tip of one of the digitate 
elements, the contents of each unit 
escape to form a vesicle in which the 
zoospores are fashioned. The latter 
usually vary from 30 to 40 in num¬ 
ber, but individual vesicles develop¬ 
ing as few as half a dozen or as many 
as 60 are not rare. Under favorable 
conditions zoospore production is ex¬ 
traordinarily abundant, the amount of 
material that can conveniently be ac¬ 
commodated in a 10 cm. Petri dish 
giving rise to numbers estimated in 
excess of 100,000 in the course of an 
hour. 
The organism evidently corresponds 
to a fungus apparently first noted in 
the literature as a variety of Pythium 
gracile Schenk by Butler (3), who in 
India found it parasitic on roots and 
base of stem of ginger (Zingiber offi¬ 
cinale Rose.) as well as on the roots 
of castor bean (Ricinus communis L.). 
Later, Subramaniam (14) investigated 
what he regarded as the same form 
more closely and set it off as a new 
species, Pythium butleri. In the mean¬ 
time it had been encountered in the 
United States as the cause of a disease 
of radishes (Raphanus sativus L.) and 
sugar beets (Beta vulgaris L.) by Edson 
(6 ), who described it as Rheosporangium 
aphanidermatum, the type of a new 
genus of Saprolegniaceae. The simi¬ 
larity and apparent identity of the 
American and Indian forms were 
pointed out by Carpenter (4 ), who 
found the fungus associated especially 
with a destructive root rot of sugar 
cane (Saccharum officinarum L.) in 
Hawaii. More recently Fitzpatrick (7) 
made Carpenter’s inferences effective 
in a nomenclatorial sense by combin¬ 
ing Edson’s specific name with both 
generic names, Pythium and Nema- 
tosporangium, the resulting binomials 
being presented as alternatives, choice 
between which was made dependent 
on the advisability of retaining or 
abandoning Schroeter’s genus Nema- 
tosporangium as distinct from Pythium. 
The genus Nematosporangium as 
defined by Schroeter (13, p. 104) was 
intended to include the forms having 
sporangia represented by filaments not 
differing from the vegetative hyphae, as 
contrasted with the forms possessing 
subspherical sporangia, which were to 
be retained in the genus Pythium. 
The distinction thus drawn is quite 
similar to that made by Butler (3), 
whose subgenera Aphragmium and 
Sphaerosporangium correspond closely 
to the genera recognized in the “Pflan- 
zenfamilien.” Recognition of the sub- 
spherical sporangium as a common 
characteristic of one group of forms is 
supported by excellent morphological 
evidence. However, the general view 
that the sporangia of the remaining 
forms consist of a simple or branching 
filament, analogous, for example, to the 
sporangium of Aphanomyces among 
the Saprolegniaceae, would appear to be 
in need of drastic revision. The spor¬ 
angia characteristic of the parasite 
causing the cucumber decay discussed 
in this paper are represented, as has 
been pointed out, by units resulting 
from the septation of conspicuously 
swollen elements, corresponding to the 
structures which Ward (15) first figured 
and described in his account of a fungus 
he designated as Pythium gracile De 
Bary, and which later Butler discov¬ 
ered in all the members of the subgenus 
Aphragmium examined by him. Neither 
of these authors appears to have ob¬ 
served the participation of these struc¬ 
tures in the formation of zoospores, 
Ward supposing them to serve as 
reservoirs of protoplasm for mycelial 
growth or the development of oogonia, 
while Butler assigned to them a prob¬ 
able capacity for surviving unfavorable 
conditions. In their studies of what 
presumably were forms identical with 
the one attacking cucumbers, Edson, 
Subramaniam, and Carpenter illus¬ 
trated and discussed the same type of 
structures as “presporangia,” “buds,” 
and “sporangia,” respectively, although 
perhaps without observing them in their 
most luxuriant development. It may 
be mentioned that even more distinc¬ 
tive development of this lobulate type of 
sporangium is exemplified in one of the 
two species with spiny oogonia found 
parasitic on watermelon fruits, the 
larger examples here being represented 
by a mulberrylike aggregation con¬ 
sisting frequently of more than a score 
of subglobose communicating elements, 
from which the contents are delivered 
through an evacuation tube into a 
vesicle giving rise to more than a 
hundred zoospores. The other spiny 
form (6) associated with decay of 
watermelons exhibits sporangia that 
may be regarded as a modification of the 
subspherical type, consisting generally 
of a subspherical part together with 
an adjacent part of one or both hyphal 
elements between which it is interca¬ 
lated, the evacuation tube arising from 
the venterlike part, or from the fila¬ 
mentous part, or very frequently from 
near the juncture of the two. Because 
Schroeter’s disposition makes no pro¬ 
vision either for this transitional type 
of sporangium or for the distinctive 
lobulate type, his scheme to be usable 
