1901] GAMETOGENESIS AND FERTILIZATION IN ALBUGO 85 
the condition presented by A. 7ragopogonis is borne in mind. 
Berlese, however, describes no such phenomena as are seen in 
A. Tragopogonis, nor does he see the coenocentrum. Thus it 
appears that in the Italian form the reduction to a uninucleate 
condition, if such a condition really exists, is of an entirely dif- 
ferent nature from that described in this paper. 
ALBUGO TRAGOPOGONIS. 
In A. Tragopogonis there is a simple fertilization. One male 
nucleus is conveyed into the oosphere, where it fuses with one 
oospheric nucleus. To understand the variation between this 
form of fertilization, also characteristic of A. candida, and that 
shown by A. Bliti and A. Portulacae, it is necessary to follow care- 
fully the stages in the development of the oosphere in the two 
former species, and to homologize them with those presented by 
the two latter. 
In A. Tragopogonis the oogonium and oospore are smaller than 
in A. Bhtt or in A. Portulacae. The number of nuclei is less in 
proportion to the size of the oogoniun, however, so that for 
each nucleus there is more available space. This obviates much 
of the dense crowding of mitotic figures seen in A. BA and in 
A. Portulacae at the time of zonation, rendering this a favorable 
type for study. The small size of the oosphere, however, makes 
it much more difficult to recognize the stages of development, 
so that even the preliminary examination must be made under 
an immersion lens. 
The early stages are similar to those described for A. Portu- 
lacae. The protoplasm flows into the oogonium, the nuclei 
enlarge, the cytoplasm masses in the center, and finally the fully 
developed stage of zonation is reached. As in A. Bliti and A. 
Portulacae, this is a well-marked developmental stage (compare 
figs. 28 and 3), although it does not stand out with quite the 
clearness that obtains in those species. There is one central 
area of dense fine-meshed alveolar ooplasm, which is very clearly 
differentiated from the filar deeply staining periplasm. The 
central region, which at this time contains a very prominent 
