STUDIES IN ARTIFICIAL PARTHENOGENESIS. 247 



effective in inducing membrane elevation. The results with 

 chlorine itself are not as good as those with mercuric chloride. 

 It is hard to regulate the amount of chlorine and only a very 

 narrow range of concentrations may be used. One drop more 

 or less of chlorine water added to 20 cc. of sea-water would often 

 determine whether the resultant solution would be effective or 

 not. Moreover the number of eggs introduced into the chlorine 

 solution was an important factor. Thus in one experiment two 

 stender dishes were each filled with 20 cc. of sea-water plus 2 

 drops of chlorine water. Many eggs were placed in one of the 

 dishes, only a few in the other. In the latter case 78 per cent, 

 of the eggs underwent partial or complete membrane elevation; 

 in the dish containing many eggs no membrane elevation occurred 

 at all. 



It is easy to suppose that the addition of mercuric chloride 

 to eggs furnishes a mechanism for supplying approximately the 

 proper dose of chlorine to the egg surface. This is probably the 

 reason that solutions of chlorine alone are not as effective as the 

 mercuric chloride. 



An argument that might be advanced against the idea that 

 the action of mercuric chloride is due to chlorine is the fact that 

 mercuric nitrate is also effective in causing membrane elevation. 

 In order to exclude the presence of chlorine, the mercuric nitrate 

 was made up in a 0.9 m sugar solution. A solution roughly 

 w/iO,ooo was prepared. The action of such a solution is very 

 peculiar. Extremely wide membranes are lifted off, membranes 

 which are quite different in appearance from the normal-looking 

 ones produced by mercuric chloride. It would be easy to show 

 that a reaction occurs between the sugar and the mercuric 

 nitrate, but no effort was made to determine the products of 

 such a reaction. However it is believed that one of the reaction 

 products causes the membrane elevation. 



From the evidence cited it is obvious that the action of mercuric 

 chloride is complex. It appears certain that the reagent does 

 not act in its original form but undergoes some sort of a chemical 

 transformation. There is good reason to believe that chlorine 

 is produced, and that this substance acts on the eggs and incites 

 membrane elevation. 



