Jan. a-Mar. 26, 1917 
Illustrations 
IX 
Page 
a, Spores with ruptured walls of other spores attached, b, Spores showing 
papillae. F.—Germinating spores. G.—A portion of a spore mass showing 
peripheral germination. H, K.—Spores germinating, in part showing ver- 
ticillate branching. L.—Secondary spores. M.—Secondary spores ger¬ 
minating. N.—A portion of vegetative mycelium from a culture. O.— 
Secondary spores. P.—Secondary spores germinating. 194 
Leaespot-Rot op Pond Lilies Caused by Helicosporium nymphaearum 
Plate 67. A.—Leaf of Nymphaearum tuberosa at 1 week after sowing conidia of 
Helicosporium nymphaearum on upper surface. B.—Leaf of Nymphaea sp. 
showing spots due to natural infection with Helicosporium nymphaearum . 
C.—Cross section of young sclerotium of Helicosporium nymphaearum from 
a commeal-agar culture. D.—Sclerotium of H. nymphaearum from com- 
meal-agar culture kept at laboratory temperature for 7 months. E.—Cross 
section of old sclerotium developed in a com-meal-agar slant culture. 232 
Plate 68. A, B.—Leaves of Nymphaea caerulea at 1 week after sowing conidia 
of Helicosporium nymphaearum on upper surface. C.—Leaf of N. capensis at 
1 week after conidia of H. nymphaearum on upper surface. 232 
Plate 69. A.—Conidium of Helicosporium nymphaearum from culture 3^ 
months old. B.—Cross section through conidium of H. nymphaearum. 
C. —Conidial group (H. nymphaearum) in situ in petri-dish culture of com- 
meal-agar at 2 weeks. D.—Conidia of H. nymphaearum . E. —Conidial 
group (H. nymphaearum) in com-meal-agar petri-dish culture at 13 days. 
F.—Water mount of conidia of H. nymphaearum from a com-meal-agar petri- 
dish culture 13 days old. G.—Conidia of H. nymphaearum from com-meal- 
agar culture.. 232 
Plate 70. A.—Cross section of normal part of leaf blade of Nymphaea odorata 
the diseased part of which is shown in B. B.—Cross section of leaf of N. 
odorata at four days after sowing of conidia of Helicosporium nymphaearum 
from pure culture to upper surface of leaf. C.—Cross section of leaf of N. 
odorata at four days after sowing of conidia of H. nymphaearum from pure 
culture to upper surface of leaf. 232 
Studies or the Genus Phytophthora 
Plate 71. A.—Mycelium of P. syringae grown on potato agar. B.—Mycelium 
of P. syringae grown on oat agar. 276 
Plate 72. Conidiophores of the various species of Phytophthora studied from 
Van Tieghem cells. A.— P.jatrophae. B.— P.arecae. C.— P.nicotianae. 
D. — P. phaseoli. E. — P. cactorum (Panax sp.). F.— P.fagi. G.— P. cac- 
iorum (Phyllocactus sp.). H.— P. faberi . 276 
Plate 73. Conidia of the various species of Phytophthora illustrating differ¬ 
ences in shape of conidia and appearance of the terminal papilla. A.— P. 
erythroseptica. B.—P. fagi. C.— P. arecae. D. — P. phaseoli. E. —P. 
parasitica. F.— P. infestans . 276 
Plate 74. —Conidia of the various species of Phytophthora illustrating differ¬ 
ences in shape of conidia and appearance of the terminal papilla. A.— P. 
cactorum (Phyllocactus sp.). B.— P. syringae. C.—P. faberi. D.— P. 
nicotianae. E.—P. jatrophae . 276 
Plate 75. Stages in the germination of the conidia and swarm spores of P« 
arecae. A. —Earlier stages. B.—Later stages. 
Plate 76. Chlamydospores and oospores of the various species of Phytoph¬ 
thora, illustrating shape and relation of the antheridium to the oogonium. 
A.—Oospores of P. syringae . B.—Chlamydospores of P. hatrophae. C.— 
