Sexual Organs of Phytophthora erylhroseptica , Pethyb . 135 
with ‘ the receptive spot of other ovum cells yet the name continues to be 
used although it has nothing in itself to recommend it. The writer ventures 
to suggest the term ‘ manocyst which at least does away with the 
implication of a doubtful homology and indicates what is probably the 
true significance. 
The manocyst in P. ery thro septica is very large in size, larger even than 
in Albugo Portidacae. It fills up almost one-half of the already diminished 
volume of the antheridium. When the safranin is well washed out it is 
seen to be filled with vacuolate cytoplasm which contains no nuclei 
(Fig. 21). The wall is thin, and now one notices that the wall of the 
oogonium is considerably thicker than in the earlier stages, and that it 
shows a double outline. The thickening extends a slight distance around 
the curve where the manocyst merges into the oogonial wall, and later, 
when the fertilization tube is pushed out in the opposite direction, the 
invagination may persist as a slight crater-like swelling still projecting into 
the antheridium. In spite of the differences due to the special circumstances 
of the case—the mode of development of the oogonium and the position of 
the antheridium—there can be no doubt that the manocyst here is homo¬ 
logous with the similar structure in the Peronosporales. Its manner and 
approximate time of formation and function are evidently the same. True, 
in this case it is bounded by a wall of oogonial origin only, whereas in all 
the other cases it is probably bounded by a wall derived from both organs, 
though Stevens ( 34 ) seems to be in some doubt about this. But the point 
does not seem to be material. Again, it does not appear here at exactly 
the corresponding time at which it is found in the other Peronosporales. 
In most of these it precedes the stage of zonation and division (Albugo 
Portulacae is an exception). Here, as has been pointed out, the zonation 
stage does not appear till after the daughter nuclei are formed, the 
sequence being the inverse of that in Albugo ; but zonation and the 
manocyst appear at relatively the same time in both. For all practical 
purposes the times correspond. In all cases it comes when the oogonium 
is in the later stages of maturation prior to fertilization, and it paves the 
way for that process and makes it possible. Probably its function is to be 
found in that it preserves a portion of the wall thin and elastic* while the 
rest is thickened, and so facilitates the elongation of the fertilization tube 
into the oosphere. Its appearance and staining reaction correspond exactly 
with those of other manocysts; in fact, it resembles the large cyst-like 
bodies of the lower Albugos, that of A . Portulacae for example, much 
more than they do the simple protuberances found in A. Candida and 
Peronospora parasitica . But there can be no doubt that all are strictly 
homologous. 
The manocyst not only appears much later, but persists later than 
usual in P. erythroseptica . and it is a conspicuous object in material of the right 
