KING: CYTOLOGY OF ARAIOSPORA PULCHRA. 
231 
occupies an area equal to one third or more of the entire diameter 
of the egg, and the coarsely vacuolate peripheral ooplasm from 
which it is sharply marked off (pi. 15, fig. 32—33). 
When the oosphere has reached the condition described, a single 
sperm nucleus and some cytoplasm are introduced into it through 
the perforation made by the receptive papilla. Although there are 
several nuclei in the antheridium before the conjugation pore is 
formed, so far as observed, only one passes into the oosphere ; the 
others degenerate. Occasionally, one can find partially empty 
antheridia showing nuclei in stages of degeneration (pi. 13, fig. 20; 
pi. 14, fig. 23). Such conditions as are represented in figures 16 
(plate 12), 18 and 19 (plate 13), which are separated by a compar¬ 
atively short interval, give ground for the inference that some of 
the cytoplasm of the antheridium enters the oosphere. In figure 16 
(plate 12) the antheridium is densely filled with protoplasm just 
before it opens; in figure 18 (plate 13) the differentiated central 
ooplasm is still well developed and the antheridium is almost empty ; 
and in figure 19 (plate 13) a strand of more deeply stained cyto¬ 
plasm can be seen extending out into the oosphere from the inner 
end of the oogonial tube. 
The sexual nuclei as they approach the center of the oosphere put 
out beak-like processes from their anterior surfaces (pi. 13, fig. 
18-22; pi. 15, fig. 34-35). In the first few cases observed, these 
pointing nuclei seemed almost triangular and the phenomenon was 
thought to be due to shrinkage although extreme care had been 
taken throughout to prevent this. The possibility of its being 
abnormal seemed to have confirmation in the fact that, as far as the 
writer is aware, approaching sexual nuclei with such beak-like proc¬ 
esses have not been observed in either animal or plant cells. As 
the investigation continued, however, these pointing sexual nuclei 
were often seen; some of them in oospores otherwise perfectly fixed 
(pi. 13, fig. 21; pi. 15, fig. 35). There is, therefore, no doubt that 
they are entirely normal. 
The possibility of their being nuclei that were dividing by con¬ 
striction was considered. If this were true, the daughter nuclei 
should, in response to surface tension, assume a spherical form when 
division is complete. A comparison of the figures cited above shows 
that these nuclei have essentially this form even when some distance 
apart. Moreover, the older oospores contain, as a rule, nuclei that 
