260 LEIGH H0ADLEY. 



the size of the experiment set up, it was necessary to use the eggs 

 of a number of females. Unless so stated, each experiment was 

 made with the eggs and the sperm of but one pair of individuals. 



IV. Experiments. 



I have chosen to deal with the experimental section of this 

 paper in three parts. In the first I will take up in some detail 

 the behavior of each solution which I used. I have taken the 

 metals up in the order of decreasing toxicity. It will be noted 

 that Mercuric chloride is apparently out of place, but as it gives 

 no membrane inhibiting point in the same sense as the other 

 metallic salts, it has been put at the end. 



The series of tests described in part b was made for the purpose 

 of comparison. The tests show the great similarity in the action 

 of the various salt solutions on the eggs and the sperm, not only 

 when they are unmixed, but also on insemination. The latter 

 includes both immediate inseminations and viability tests. 



Under c I have summarized the experimental data. There is 

 also a table there that shows both the membrane-inhibiting 

 concentration and the cleavage-toxic concentration for each of 

 the metals. 



a. Data on the Various Metallic Salts. 



i. Gold Chloride. — On July 20, 1922, a 1 per cent, stock solu- 

 tion of AuCl 3 was made in distilled water and used for establishing 

 concentrations in sea-water as shown in Table la. These were 

 prepared separately for, and at the time of each experiment. 

 A series of tests was then set up to establish the effects of various 

 concentrations on eggs which were inseminated immediately in 

 the solutions. The results are shown in the accompanying 

 Table la. It can be seen on examination, that one part of AuCl 3 

 to 1,500,000 parts of sea-water will completely inhibit membrane 

 elevation. At I : 600,000 and I : 300,000, narrow hyaline zones 

 appear around the eggs after an exposure of about five minutes 

 to the solution, but upon examining the control, it was found to 

 be merely the first indicium of cytolysis in the egg. 



A series of tests was then made with the purpose of determining 

 what concentration is necessary to inhibit cleavage when the 

 eggs are transferred to the solutions five minutes after insemina- 



