410 
Journal of Agricultural Research 
Vol. XXIX, No. 8 
Observations on development and 
fertilization have been made repeatedly 
on living material growing in hanging 
drops of oatmeal decoction, in which 
the young fruiting bodies appear with¬ 
in two days (Pis. 4 and 5). The an- 
theridium is in contact with the 
oogonium at a very early stage, before 
either has been cut off by a septum. 
At this time it is larger than the 
oogonium and partly wrapped around 
it, and presents the characteristic 
flaring shape. It arises from a neigh¬ 
boring hyp ha, from an adjacent branch 
of the same hypha, or immediately be¬ 
neath the oogonium. The latter is 
formed by the swelling of a hyphal tip,, 
finally outgrows the antheridium, and 
both are cut off by septa (PI. 5, B). 
Mature oogonia average 18.56 ju in 
diameter (300 measurements) and 
range from 13.2 /u to 23.31 ju- 
MICRONS 
Fig. 2. —Frequency curves of oospore and oogonium measurements, 300 of each 
EXPLANATORY LEGEND FOR PLATE 5 
A. —(a to h), stages in formation and germination of zoospores 
B. —Three stages in early growth of sexual bodies 
C. —Fertilization: (a), Beginning of oosphere contraction; (6), passage of antheridial contents 
into subjacent oosphere through hole in fused walls; (c), oosphere rounding up; (d. e,f) 
exospore wall formation by clear band extending around oosphere periphery. The 
clear band in (e) and (/) is drawn at twice actual width, to render it visible at scale 
of reproduction 
D. —Oospores, showing attachment on slender stalk and relation to antheridium 
