Artificial Parthenogenesis 121 



the following facts. The writer has shown that it is 

 immaterial whether the eggs are treated first with the 

 hypertonic solution and then with butyric acid or the 

 reverse, if only the eggs remain longer in the hypertonic 

 solution when the hypertonic treatment precedes the 

 butyric acid treatment. It was stated in the beginning 

 of this chapter that the development of the egg can 

 be induced by hypertonic sea water, and we know the 

 reason since hypertonic sea water is a cytolytic agency. 

 The writer found that when we expose unfertilized 

 eggs of purpuratus for from two to two and a half- 

 hours to hypertonic sea water they will often not de- 

 velop and only a few eggs will undergo the first cell 

 divisions, then going into a condition of rest. When 

 these eggs, both the segmented and unsegmented, were 

 treated twenty-four or thirty-six hours later with 

 butyric acid, so that they formed a membrane, they 

 all developed into larvae without further treatment. 

 It is impossible to apply Lillie's theory to these facts, 

 for the simple reason that the treatment with hyper- 

 tonic sea water was just long enough to induce de- 

 velopment in some eggs and hence according to Lillie's 

 ideas must have increased the permeability of these 

 eggs. Yet these same eggs were induced to develop 

 normally when subsequently treated with butyric 

 acid, which according to Lillie also acts by increasing 

 the permeability. Nothing indicates that the treat- 

 ment of the eggs with a hypertonic solution diminishes 



