1899] THE COMPOUND OOSPHERE OF ALBUGO BLITI 155 
may only conjecture whether or not it is derived from the anther- 
idium wall, The history of the papilla beyond the stage shown 
in fig. 54 is not clear. In this condition the structure is very 
thin-walled and its contents vacuolate, resembling a large irreg- 
ular compound bubble. Whether the delicate wall now bursts or 
the contents are gradually withdrawn into the oogonium is uncer- 
tain. At all events, the papilla in later stages leaves no trace of 
its former existence. There follows at a later period conditions 
(figs. 56, 57) which show that there is certainly a movement of 
the cytoplasm in the opposite direction, the antheridium extend- 
ing a process with a cell wall through the opening into the oogo- 
tum. The first surge of the cytoplasm from the oogonium into 
the antheridium may be due simply to the unequal conditions of 
turgor in the two structures, but it is possible that there is also a 
phylogenetic significance in the phenomenon. The occurrence 
of similar structures in A. candidus and A. Portulace shows it to 
te of some import. Such a papilla in a much less highly devel- 
“a form is figured by Wager and referred to as the receptive 
pila. 
The antheridial tube presses into the oogonium in the form, 
aa thin-walled process (figs. 56,57). It is filled with 
ie aaa that greedily absorbs and retains stain, and is 
rina‘ per y @ sheath of dense oogonial cytoplasm. The nuclei 
ae = ag antheridium, none entering the tube at this time, 
ie indistinguishable in size and structure from those in the 
‘wpa They are also in the spirem condition, similar to 
Scribed for the oogonial nuclei, The description of the 
further develo 6 ae Z foll 
Oh toa pent of the antheridial tube is deferred, to follow 
of the differentiation of the compound oosphere. 
D 
'FFERENTIATION OF THE COMPOUND OOSPHERE. 
The : : 
Previous description carries the history of the sex organs 
up to ‘ 
ody time when the antheridial tube has penetrated the 
Cor, l m one fourth or one fifth the diameter of that structure. 
related wit 
°Ccurs the jog the further development of the tube there 
erentiation of the periplasm and ooplasm, and the 
