226 Barrett . — Development and Sexuality of some 
Fig. 38 illustrates that condition. It shows the appearance of the 
nuclei after the last division, and around which the individual zoospores are 
to form. Chromatin masses are arranged about the nuclear membrane in 
more or less irregular areas. It is in this stage that the sporangium may 
undergo a period of rest. 
I have observed no indication of an amoeboid or otherwise irregular 
stage of the parasite. A. Fischer ( 11 ) describes such a condition as common 
for O. ( Pseudolpidium ) Saprolegniae even after the parasite had reached 
some size (see PI. X, Fig. 5, a-d). In the young living specimens it is 
sometimes very difficult to determine the limits of the host and parasite 
protoplasms, but in stained sectioned material such a difficulty disappears, 
for the reason that the protoplasm of the parasite has a different affinity 
for stain than that of the host. There is no indication whatever of a fusion 
of two or more parasites to form one, and it seems very evident that each 
zoospore after entering the host maintains its individuality and gives rise to 
a single sporangium. In other words, no plasmodium is formed. In abun- 
dantly infected material one frequently finds in section a number of very 
small individuals, sometimes still uninucleate, accompanying the larger ones 
in swollen hyphae whose protoplasm has been exhausted. In some cases 
these small parasites have taken on a mature state and may give rise to 
a small number of zoospores. 
Fig. 39 represents a portion of a section of a sporangium in the 
vacuolate resting condition, and of the same age as that from which 
Fig. 38 was drawn. The former was killed in weak Flemmings solution, 
the latter in medium chrom-acetic acid. This section shows very clearly 
that the uninucleate spore centres are not only definitely formed at this 
time, but that fragmentation has, at least partially, taken place. The nuclei 
take a deeper stain than those shown in Fig. 38, in which lines of segmenta- 
tion of the protoplasm are not visible. There is no apparent indication of 
vacuoles in the young spores, which indicates, it seems, that during the 
resting period of the sporangium the water of imbibition of the spore centres 
is at a low ebb. 
From this and many other similar sections I think it is evident that 
the spore centres are formed before the resting period of the sporangium 
ensues. The changes which take place subsequently to the resting period, 
and which have been supposed to give rise to the fashioning of the spore 
centres, are merely the phenomena accompanying the final stages in the 
development of the zoospores. 
So far as could be determined, fragmentation of the protoplasm is 
simultaneous throughout the sporangium much as described by Dangeard 
(7) for the primitive cell of Synchytrium Taraxaci. When exit tubes are 
present at this stage their protoplasm likewise shows segmentation into 
spore centres. 
