Holden and Harper—Nuclear Phenomena . 71 
due to shortening and this in turn reduces the number of coils 
or loops, (Fig. 16). As the threads become thicker they stain 
more deeply, while the nucleoli at this stage stain less deeply 
and no longer preserve a smooth plump outline' but show mi¬ 
nute irregularities. At a later stage the nucleoli show still fur¬ 
ther changes of the same sort. They are less deeply stained 
and instead of being irregularly oval, may show any irregular 
shape and the smaller irregularities in the surface become more 
prominent, (Fig. 17). At a little later stage the nucleolus disr 
appears entirely and it seems probable that it has been gradu¬ 
ally broken up and dissolved. In the later spirem stages the 
nuclear membrane disappears entirely and the chromatin 
thread lies in a finely granular material, not sharply distin¬ 
guished from the surrounding cytoplasm, (Figs. 16 and 17). 
The thread is seen now to have been split longitudinally, (Fig. 
17). In some portions the halves are still in contact while in 
others they are quite widely separated. That a longitudinal 
splitting occurs thus in the prophases in this fungus nucleus, 
is of considerable interest as establishing another point, of agree¬ 
ment between thallophyte nuclei and those of the higher plants. 
The later separation of the daughter chromosomes on the spin¬ 
dle is merely a distribution of the split halves of the original 
chromatin thread. It is very noticeable in preparations of this 
stage that the spirem thread is not continuous. This is plainly 
shown in Figs. 16 and 17, and it is quite probable that this con¬ 
dition indicates a segmentation into chromosomes. The stages 
in the formation of the spindle have not. been found. The 
equatorial plate stage on the other hand, here as in most, other 
cases, is relatively easy to find. It is an interesting and char¬ 
acteristic figure and differs entirely from that given by Poirault 
and Eaciborski for C oleosporium, Euphrasiae and also but in a 
somewhat less degree from that given by Juel for Coleosporium 
campanulae. The figures in our preparations are extremely 
sharp and clear and agree much more nearly with those of other 
mitoses than do those of the authors named. The characteris¬ 
tic structural features of this stage in fungi and algae gener¬ 
ally are all present. Polar radiations, central bodies, spindles 
and chromosomes are all very sharply differentiated. The cen- 
