EFFECT OF ARTIFICIAL MEMBRANE FORMATION 7? 



It is of interest to add that fertilized eggs can also be caused 

 to show this process of droplet formation during the first seg- 

 mentation, namely if they are caused to segment in an abnormal 

 solution. It depends upon the degree of abnormality whether 

 or not such eggs can afterward develop into normal larvae. 

 When unfertilized eggs of S. purpuratus were exposed for about 

 two hours to a hypertonic solution and fertilized with sperm 

 immediately after they were taken out of the solution they were 

 able to develop, but the first segmentation occurred often with 

 droplet formation in the plane of division. When they were 

 fertilized after they had been in the normal sea-water for some 

 time they segmented normally. 



While the artificial membrane is enough to initiate the act 

 of development, something is abnormal in the egg in so far as the 

 process of cell division leads to its destruction. We should 

 therefore expect that if we inhibit the process of cell division, 

 the eggs would not perish. This conclusion is correct. 



It has been mentioned that cell division can be prevented 

 in the fertilized sea-urchin egg by depriving it of oxygen or 

 stopping oxidation by certain poisons, such as KCN. We will 

 now proceed to show that if we deprive the sea-urchin egg of 

 oxygen after artificial membrane formation, or put it in sea- 

 water with a little KCN or chloral hydrate, we then inhibit the 

 disintegration described above. 1 Membrane formation was pro- 

 duced in the eggs of a sea-urchin by treating them with butyric 

 acid. The eggs were then divided into three portions. One 

 remained exposed to the air, a second was placed in a flask 

 through which was passed a stream of pure oxygen, the third 

 in a flask of sea-water out of which practically all air had been 

 driven by a stream of hydrogen, and in which the current of 

 hydrogen passed through the vessel during the whole of the 

 experiment. The eggs which had been exposed to oxygen in 



1 Loeb, Untersuchungen ueber kunstliche Parthenogenese, p. 483; Biochem* 

 Zeitschr., I, 192, 1906. 



