302 E. E. JUST. 



such as : increased oxidation, increased permeability, varying 

 susceptibility to heat, cold, ether, lack of oxygen, KCN, etc. 

 They constitute indicia of cell division regardless of fertilization. 

 An egg following insemination shows increase in viscosity, per- 

 meability, oxidation, and susceptibility to KCN. But these in- 

 creases are not the "cause" of activation; they are the expres- 

 sion of the beginning of the rhythm of cell division. 



If this position be tenable, if indeed these so-called indicia of 

 cell division be simply the expression of cell division should we 

 not expect to find that there are not such great changes in per- 

 meability, oxidation, or susceptibility to KCN in the case of an 

 egg inseminated while in a stage of mitosis? Thus, in the sea 

 urchin egg, in which maturation is complete and the nucleus at 

 rest at the time of insemination, we should expect to find great 

 physical and chemical changes due to the initiation of cell-divi- 

 sion; but in an egg like that of the starfish inseminated during 

 maturation we should not get such great changes. And this in- 

 deed is the case. 



Loeb ('13) found, for example, in the sea urchin egg "that 

 immediately after fertilization the egg consumed five to seven 

 times as much oxygen as before fertilization." But he found 

 conditions entirely different in the starfish egg : " No noticeable 

 increase in the rate of oxidation is caused in this egg through 

 the entrance of the spermatozoon. This is intelligible from the 

 fact that those oxidations which lead to nuclear division were 

 already going on in the eggs at the time the spermatozoon en- 

 tered." In other words, insemination in the starfish egg does 

 not initiate division and so does not increase the rate of oxidation. 



R. S. Lillie has studied the permeability changes in fertilized 

 eggs of Arbacia and Echinarachnius, both of which show the same 

 kind of permeability changes. Thus, he found that Arbacia 

 eggs take up water several times more rapidly after fertilization 

 than before ; so great is this difference as shown by the increased 

 volume of the fertilized eggs that fertilized and unfertilized eggs 

 in the same dish of hypotonic sea-water are easily separated. As 

 would be expected, unfertilized and fertilized eggs differ in 

 their response to hypertonic sea-water; the fertilized eggs lose 

 water much more rapidly. Echinarachnius eggs behave similarly 



