1901] GAMETOGENESIS AND FERTILIZATION IN ALBUGO 251 
each is accompanied by a pectiniferous formation from which 
the middle region of the oogonium is exempt. 
Occasionally, by the formation of the oospore wall, a super- 
numerary antheridial tube is pushed aside in the periplasm. It 
then swells until it assumes a club-shaped appearance as it 
presses against the wall. In such cases the pectiniferous layer 
is formed over the whole mass, consisting of the mass of sperm 
nuclei and the remains of the antheridial tube (fig. ¢8). Con- 
ditions like these result, in the ripe spore, in a structure which 
looks much as though an antheridium lying beside an oospore 
had been encased (fig. 49). Such malformations may be dis- 
tinguished from antheridia by the still persistent oogonial wall, 
which would of course not include the antheridium, but do 
include these masses. 
If emanations from the antheridial tube stimulate the cyto- 
plasm of the oogonium to form the pectiniferous layer, why 
does not the tube become coated as it penetrates the oosphere ? 
This question probably receives its answer in the fact that the 
ooplasm has not the power to form pectin. It produces cellu- 
lose deposits, but not even in teratological cases (jig. 47) does 
it give evidence of any ability to form the pectiniferous layer. 
It is also notable that the ability to deposit the characteristic 
thick cellulose layer and to accumulate the typical oily globules 
is limited to the ooplasm. It seems, therefore, that in the 
activities leading to zonation there is a differentiation of the 
cytoplasm, that a capability vested in the oogonial cytoplasm is 
lost to the ooplasm, and its manifestation in later stages becomes 
limited to the periplasmic regions.* Whether this differentiation 
consists merely in a shifting of partially elaborated products of 
metabolism or in a segregation of living cytoplasm into two 
regions, one possessing a different constitution from the other, 
must be left an open question. ‘ 
The stimulating effect from the antheridium may be mant- 
fested when the tube has penetrated only half way to the center 
® The figures of Magnin (1895, fg. 71) might at first glance appear to contradic 
this, but Magnin’s figures represent callose which is really present both in inner and 
outer walls, 
