Sexual Organs of Phytophthora erythroseptica , Pethyb . 139 
The tube contains a single nucleus near the tip, and after it a large 
part of the cytoplasm of the antheridium passes in. Fig. 26 shows this 
actually in the act. This is in agreement with Hartig’s ( 19 ) account of 
Nozemia Fagi , and in agreement with most other workers on Pythium and 
on Phytophthora , but in direct contrast to de Bary’s ( 2 ) rendering of the 
procedure in his account of Phytophthora . All authors agree that the 
antheridia of Pythium are left almost empty after fertilization, and this 
is the impression one gets here too from a study of both living and fixed 
material. The remaining nuclei and a small amount of cytoplasm are left 
behind. Two very small deeply staining bodies, possibly the remains of 
two nuclei, were once found in the base of a tube which had already 
functioned, but this is quite exceptional. The tube having penetrated 
a short distance into the oosphere delivers its nucleus and cytoplasm, and 
is then in all probability cast out. The male nucleus is small and shows 
little structure beyond a large nucleolus. In one case at least it was found 
somewhat pointed at one end (Fig. 25, a). Meanwhile the female nucleus 
is increasing in size and staining power. As a rule it remains small and 
stains lightly until after fertilization, but these events are evidently not 
entirely interdependent, because now and then one sees cases in which the 
fertilization tube is formed rather early, while the periplasm is still fully 
present; again, fertilization may be delayed till the oosphere nucleus has 
gained in size and chromatin and the contraction of the periplasm is more 
marked. This is usual in the whole group. 
It seems likely that the oosphere contracts somewhat during or after 
fertilization. In many cases the periplasm is so exceedingly scanty that 
the degenerating nuclei are only just perceptibly removed from the 
oogonium wall. When the periplasm has disappeared the young oospore 
is never so large. The cytoplasm of the oosphere also becomes markedly 
denser at the same time. However little or much this contraction may 
be, the limits are soon reached, and the oosphere, now containing one 
male and one female nucleus, surrounds itself with a thin wall, which 
Stevens has termed the primitive wall (Fig. 27). 
Outside this there is nothing at this time in the way of periplasm 
except the remains of the nuclei which still stain deeply. Except these 
and an isolated fragment or granule perhaps, the space surrounding the 
spore is empty. The greater aggregation of periplasm about the fertiliza¬ 
tion tube which de Bary and Woronin ( 5 ) found in P. omnivor a, in which 
they found little or none elsewhere, has not been seen. Neither are the 
trabeculae, described by Pethybridge ( 27 ) for this Fungus and for P. Arecae 
by Coleman ( 11 ), very evident in the writer’s slides. They must stain very 
faintly, and it is possible that they do not persist very long. 
There seems to be little point in dwelling on teratological cases unless 
they appear to possess a phylogenetic or other significance. Curved ferti- 
