io 
Journal of Agricultural Research voi. xxm, no. x 
points upon which emphasis is deemed desirable, and, of course, of any 
new points that may be brought out. 
Morphologically distinct sporangiophores of this fungus have never 
been observed by the writer in nature. Sporangia have been observed, 
but always attached to hyphal branches that could not be distinguished 
by any morphological characters from other aerial hyphae of the fungus. 
In pure culture this same condition seems to exist. Attempts were made 
with the use of Van Tieghem cells to produce sporangiophores, as was 
done by Rosenbaum with several different species of Phytophthora ( 21 ). 
In the aerial hyphae that developed, sporangia could be seen on irreg¬ 
ularly branched hyphae. In no case were clusters of sporangia seen, 
such as are pictured by Rosenbaum. Plate 8, D, E, F, and Plate 9, G, 
H, are camera-lucida drawings of sporangia as found in pure cultures 
attached to the hyphae. 
M/CRONS. 
Fig. i.—G raph showing the variation in length and width of sporangia of Phytophthora parastiica 
var. rkei. 
Sporangia are variable in size and shape but on an average would be said 
to be comparatively large, and of the short, ovate type rather than the long, 
slender kind. Figure 1 shows the results of 200 measurements and shows 
graphically the sizes of greatest frequency. It will be seen that practically 
all of them fall within the limits of 33 to 48 /x by 24 to 39 /x, the mode 
being 39 by 30 /x, the average 41.03 by 30.85 /x. The ratio of length to 
width varies from 1.2 to 1.5, 1.3 occurring more than any other. Pa¬ 
pillae are mostly apical, an occasional lateral one being found. They 
are prominent, the average of 25 measurements being 2.75 n in height and 
5.9 /x in width. Sporangia are mostly terminal, but frequently intercal¬ 
ary. Intercalary sporangia are sometimes normal in both size and shape, 
but many functioning sporangia have been observed, very small, spheri¬ 
cal, and lacking the apical papillae. Such were considered out of the 
ordinary and were not included in spore measurements. The wall of 
the sporangium gives the true cellulose reaction to the chloroiodid of 
