176 BOTANICAL GAZETTE [MARCH 
Its development is simple. A somewhat enlarged wall cell of a 
young conceptacle divides transversely, forming two cells much alike 
in size and contents (jig. 29). The inner cell, which is the homologue 
of the stalk cell of the female organ in Fucus, cannot be distinguished 
from neighboring wall cells shortly after its formation. The outer 
cell, which has a free surface toward the interior of the conceptacle, 
increases greatly in size and soon becomes the spherical oocyst. Fig. 
30 represents a young oocyst and its sister cell, already unequal in 
size. There now follows a long period of growth, during which the 
oocyst attains a remarkable size, finally containing a great quantity of 
reserve material, many chromatophores, much cytoplasm, and a large 
nucleus. The mature organ, drawn under a lower magnification than 
fig. 30, is represented in fig. 31. No trace of its sister cell could be 
found. 
The oocyst of Sargassum develops but one egg. The mitosis within 
the wall cell whose division produces the oocyst is normally the only 
mitosis in the process of oogenesis. Particular attention was given to 
this point. The one nucleus of the oocyst remains in a resting 
condition throughout the entire period of the growth of the cell, and 
therefore becomes the nucleus of the egg. In the other genera of the 
Fucaceae, as is well known, there are three mitoses within the oocyst, 
resulting in eight nuclei. Each of the eight nuclei may become a 
center for the development of an egg as in Fucus, or some nuclei may 
degenerate and a less number of eggs be formed, as in Ascophyllum 
and Pelvetia. It might be supposed from these conditions in the 
Fucaceae that the oocyst of Sargassum would show similar nuclear 
divisions and degeneration, but this is not the case. The mitoses 
characteristic of oogenesis in Fucus are normally suppressed in Sar- 
gassum. The tendency in the Fucaceae to reduce the number of eggs 
produced by an oocyst reaches its culmination, therefore, in Sargassum. 
It is interesting to note that Sargassum still gives proof that it be- 
longs to the reduction series which has its beginning in Fucus and 
allied forms that produce eight eggs in an oocyst. Out of the great 
number of conceptacles examined, one oocyst was formed which con- 
tained two eggs, and two oocysts which contained eight. The oocyst 
with two eggs was formed in an immature conceptacle that held five 
normal oocysts. The two eggs appeared fairly vigorous. One of the 
