8 MILDEWS. RUSTS AND SMUTS 
oospore. Antheridia slender, originating below the oos- 
phere. 
Differs from all other genera in the vegetative and re¬ 
productive mycelium not being differentiated. Some 
species are destructive parasites. 
Pythium debaryanum, Hesse; Massee, Brit. Fung., p. 
133- 
Mycelium vaguely branched, sometimes with an occa¬ 
sional septum, colourless ; zoosporangia globose or broadly 
elliptical, terminal or intercalary, with an indication of a 
wart or papilla at the tip, producing zoospores ; chlamydos- 
pores resembling the zoosporangia, but with thicker walls ; 
oospheres globose, wall not perforated, 21—25 /x, solitary 
in the oosphere, globose, 15—18 /x, wall thick, smooth, 
colourless, on germination producing a germ-tube, and not 
zoospores. Fruit produced outside the host. 
Syn. Pythium equiseti, Sadebeck. 
Pythium vexans, De Bary. 
Pythium autumnale, Sadebeck. 
Saprolegnia schachtii, Frank. 
Parasitic on a great number of different kinds of plants, 
more especially during the seedling condition, where it is 
the cause of the disease known as “ damping off ” of seed¬ 
lings. Amongst its hosts are Camelina sativa, Lepidium, 
Sinapis, Capsella, Beta, Trifolium repens, Spergula arvensis, 
Zea mays, Panicum miliaceum ; amongst cryptogams may 
be mentioned the prothallus of Equisetum autumnale, L. 
cernuum, and L. annotinum ; prothallia of Todea and 
Polypodium, amongst ferns; prothallus of Lycopodium 
inundatum ; Pellia epiphylla and Plagiochila asplenioides. 
Germany, France and United States. 
Pythium proliferum, De Bary; Massee, Brit. Fung., 
P. 134- 
Mycelium usually copiously branched; zoosporangia 
terminal on short branchlets, egg-shaped or lemon-shaped, 
with a wart at the tip, zoospores kidney-shaped, with two 
cilia, escaping through the deliquescent wart, a second 
zoosporangium often developed within the first empty 
one; oospheres mostly produced in the substance of the 
host, globose, 18—24 /x; antheridia, i—3, mostly 2 ; oos¬ 
pore only one in an oosphere, smooth, 15—18 /x, germinating 
by the protrusion of a germ-tube. 
