ont « a Tenn —s —— 
1901 | GAMETOGENESIS AND FERTILIZATION IN ALBUGO 81 
female nuclei. These two divisions may be recognized at a 
glance, inasmuch as. the mitoses are simultaneous for all the 
nuclei concerned. The nuclear figure of the second mitosis dif- 
fers from that of the first in that the nuclear membrane disap- 
pears and there are fewer spindle fibers. The second mitosis 
usually affects only those nuclei that lie in the clearly differen- 
tiated oosphere. 
Peculiar activities are present in the center of the oogonium 
shortly before zonation, which lead to the formation of the coe- 
nocentrum. This structure, much less conspicuous and much 
more ephemeral in A. Portulacae than in A. Bit, is of the same 
general nature, however, and needs no special description. The 
central globule is found only rarely and is very small. 
The development of the antheridium of A. Portulacae is sim- 
ilar to that of A: Bliti in its general features. Simultaneously 
with the mitosis of the oogonium two mitotic divisions occur in 
the antheridium, but the difference which is so clearly apparent 
between the nuclear figures of the first and second mitoses in the 
oogonium is not found in the antheridium. The antheridial 
cytoplasm stains darkly with the gentian violet, and resembles 
the periplasm rather than the ooplasm of the oogonium. The 
antheridia lie closely appressed to the oogonia, and it is not 
unusual to find more than one adhering to the same oogonium, 
a condition much more rarely seen in A. Bhi. 
A slight papilla is developed from the oogonium into the 
antheridium at their point of contact. This is the ‘‘receptive 
papilla,” first described by Wager (1896) tor A. candida, and it 
reaches most remarkable proportions in A. Portulacae (figs. 1, 5; 
6). In its early stages it resembles the receptive papilla of A. 
candida and A. Bliti, being merely a slight protuberance extend- 
ing from the oogonium to the antheridium.t. In A. Portulacae, 
however, it reaches much greater proportions ( jig. 5 ). Its 
development occurs at a later period than in the other species, 
usually after the differentiation of the oosphere or even during 
* The account of the structure in 4. Bliti (Stevens 1899) traces the growth of the 
papilla in detail. 
