132 Murphy,—The Morphology and Cytology of the 
present is as a rule about eight to ten, but it is very variable. A certain 
number degenerate: how many it is not easy to say. The number present 
during mitosis is probably not more than four, so that the proportion of 
nuclei left to those originally present is about the same as in the oogonium. 
The cytoplasm never exhibits flow structures nor are the nuclei ever linear. 
As good mitotic figures may be found in the antheridium as any in the 
female organ (Fig. 17), and the details of nuclear division are the same 
for both. The spindles are often oriented in the direction parallel to 
the stalk of the oogonium, this being necessary on account of the very 
limited dimensions of the body. Afterwards the same fate befalls the 
supernumerary nuclei as those of the female organ, nor is it easy to say, 
until it is seen in the fertilization tube or in the oosphere, which one will 
serve as the functional male nucleus. It too remains very small until it 
reaches the oogonium, and it is never clear what fate overtakes the others 
after division. It is probable that they are reorganized for a very short 
time after telophase, but that they never reach the stage of resting nuclei 
again. Their deep-staining, undifferentiated remains persist long after 
fertilization has taken place and the antheridium is almost empty. 
Nuclear Divisio?i. 
The nuclei which pass into the sexual organs are very small in size. 
A general account of their appearance has been given, and the details of 
the earlier phases need not be gone into further. After those in the 
oogonium have resumed their spherical shape all the nuclei, in both 
oogonium and antheridium, behave similarly. This is to be borne in mind 
even though the oogonium be mentioned oftener than the antheridium in 
the discussion of nuclear phenomena. 
While a relatively large number of nuclei are degenerating in both 
organs the remaining«ones increase proportionately in size. The chromatin 
masses and the nucleolus stand out clearly, but the presence of a centrosome 
could not be definitely established at this stage. As soon as the degenera¬ 
tion process is over the survivors have attained their full size and have 
become arranged in the form of a hollow sphere. They have now entered 
into prophase. Naturally all the details of division cannot be followed in 
nuclei so small, and it is not clear how the chromatin is arranged on the 
linin network or how the spireme thread originates. Beaded chains have 
been seen, and they are no doubt to be interpreted as the beginnings of the 
continuous thread. The spireme itself is a conspicuous figure (Figs. 37 
and 38). The nucleolus is still large, but not so large in proportion to the 
size of the nucleus as in the earlier stages. The spireme thread is stout 
and apparently rather shorter than it sometimes is. In what seem to be 
the concluding stages, when it is near segmentation, it appears to be much 
