No. 466.) SICDIES OM PLANT CELL.—VIHL. 735 
studies on Albugo showed that the coenocentra exert a chemo- 
tactic influence upon the nuclei in their vicinity, drawing them 
towards the mass of granular material in this favored region of 
the cell and it is clear that they are greatly benefited in this 
situation since they increase in size while the nuclei at the 
periphery break done. This subject is discussed in detail in my 
paper on Saprolegnia (Davis, :03, pp. 240-243) a form which 
also illustrates exceptionally well the same principles of a sur- 
vival of certain nuclei among many which degenerate, because of 
their favorable position in the central region of the eggs in close 
proximity to coenocentra. There are then undoubtedly regions 
of the cell more favorable for the nutrition of nuclei than others 
and the positions of these may be marked by morphological 
characters as illustrated in the caenocentra. That similar dyna- 
mic centers may also be present when there is little morphologi- , 
cal evidence of their existence is indicated in the processes of 
oógenesis in Vaucheria (Davis, :04) which exhibits the same 
principles of extensive nuclear degeneration as are found in the 
Peronosporales and Saprolegniales and the survival of a single 
nucleus in the oógonium, apparently because it comes to lie in a 
mass of granular cytoplasm near the center of the oógonium. 
