( ‘akxp: — Brou'ii Roi of 
2 s 
normal method. .Discliarge of zoos])ores commenees an hour and a 
lialf to two hours after the spores in Avater and continues 
for about one hour. The first indication of zoosj)ore formation 
noted is a movement of the ])roto])]asm of tlie spores causing it to 
]oiind into a central mass. This mass then l>reaks u]) into zoos- 
])oirs whicli rapidly move towards the apical end of the spore Avliere 
th(‘ papilla is a])parently distended into a A^esicle. This vesicle has 
]iot ]>een seen, hut the paj>illa disappears, and the subsequent move- 
ment of the zoos])ores certainly suggests tlie jiresence of a vesicle. 
Tlie 7oos])ores are at first attached by their flagella and in some 
cases two liave been noticed to remain attached for some minutes 
lifter emergence. Kach sjiore is coni])resse<l as it sipieezes through 
the aperture. Sometimes tAvo Jam in the opening and either finally 
escajte or remain blocking tlie exit, jirevimting the enuu’gence of tlie 
remainder of the zoospoi-es. Tnimediately on leaving tlie sporan- 
-ginm the zoosjiores collect in a mass suggesting tlie pi’esence of a 
A'esicle. and then dart in all directions, tlie whole jirocess from tlv 
first signs of movement Avitliin tlu' sporangium taking only two or 
tlii-ee seconds. When killed with iodine solution the zoospores 
average 9.1) x S dmmm, (range S.7- -ll.d x 7.8 — 9.d) . "When in iuoav- 
ineiit they a])])ear to be about 11 x 9mmm. They are more or less 
kidiiey-sliajied with tAvo flagella attached to the concaAm side, ou;' 
longer than the other. The average length of the longei’ is Id.fimmm.. 
and of the shorter (i.lmmm. The number of zoospores formed in a 
sporangium vai'ii's from d to 20. Occasionally the Avhole protopins 
mil- contents .are ilisdiarged in an undifferentiated mass. After 
swimming for about 80 minutes the zoosjiores round off*, ({('rmin- 
ation commences within 12 to 24 hours, one or more germ-tubes 
emerging. Kot inf reijiumtly sonu* zoospores round off* Avithin th'- 
sporangium . 
In citrus leaf and fruit tissms and on Colocasia sp. leaf tissue 
liarticidarly tlu' leaves both of citrus and Coloeasia^ and to a lesser 
(‘xteiit in ])otat() dextrose agar, oat juice agar, French bean aga^. 
jmme juice agar, and Avheatmeal. oogonia Avitli amphigynous 
antheridia are formed. In leaf tissues in Avater or on potato dex- 
trose agar the number of oogonia formed very large, the tissue 
being filled Avith them. Very occasionally the antlieridia arc 
jmragyuous (Plate I \' ) . Antlunudia and oogonia as far as could 
be (il)ser\a‘d appear to come from eitlier the same or different 
hyphae. On affected tissues oogonia are developed in about a Aveek 
at 10-150 (’_ j], culture in from 10 to 14 days. Tlu‘ oogonia, Avhich 
are round to ovoid average 40.8mmm. in greatest length Avitli a range 
of 22.4 — 56mmm. (100 measurements from orange leaf tissue o'' 
potato dextrose agar). Oospores are s])herical and aA'erage 35mmm. hi 
diameter Avith a range of 22 to 45.(immm. The antherida are* hya.liiu‘ 
and A’ery persistent. The oospores range from yelloAV to tawny 
