WATER 



upon the stage in the division-cycle of the egg. The forma- 

 tion of water-drops thus is also a cyclical phenomenon. 



From these experimental findings we may draw the fol- 

 lowing conclusions concerning the behavior of water in 

 these eggs. 



First, water leaves the cell as discrete drops. This does 

 not imply that all the water that leaves the cell is in this 

 form. But since, as is shown in these experiments, water 

 leaves the cells in visible drops, a theory concerning the 

 exit of solutions as ions can not apply to these drop-forma- 

 tions. Visible drops of water are of more than even mole- 

 cular size. 



Second, the change in shape of the drops as they cross 

 the barrier of the ectoplasm suggests that they pass through 

 canals whose diameters are less than theirs. Now the ecto- 

 plasm shows chambers, the spaces between the radial pro- 

 jections. Since the diameter of the drops is less than that 

 of these ectoplasmic chambers, the latter can not be the 

 canals concerned. The canals therefore through which 

 the drops pass though not sub-microscopic are smaller than 

 these ectoplasmic spaces. The experiments thus strongly 

 indicate that under these conditions the ectoplasm is a 

 sieve with extremely small openings. 



Third, the yolk-spheres take up water from the cyto- 

 plasm. The yolk in the Nereis-egg is a mixture of lipoid 

 and protein.^ This combination breaks down as water 

 accumulates in the cell and enters the yolk-spheres. Lipoid 

 escapes from the yolk-spheres into the cytoplasm. When 

 water leaves the cell, water also leaves the yolk and the 

 lipoid again enters the yolk. In hydration and dehydra- 

 tion of the yolk the lipoid moves out of and into it. Oil 

 moves out of the yolk as water moves into the yolk-spheres 

 leaving them skeins of protein. As water moves out, oil 



^ See Konopacki, iQ2g. 



135 



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