290 Charles R. StockarJ 



Solutions of MgSOi and Mg{lS[0^2 ^" Sea-water 



Sea-water solutions of MgS04 prepared in a similar manner 

 to the MgClj solutions above were employed. The following 

 strengths J m, i| m, i| m, i| m, i| m, if m, fo m, ff m, ^ m, 

 11^ M, 11^ M, and 1^ M were ineffective, the eggs in these solutions 

 developing normally with very few deaths at any stage. 



Mg(N03)2 solutions in sea-water caused typical cyclopia indis- 

 tinguishable in all respects from that produced in MgClj. The 

 following strengths were used: if M, i| m, if m, if m, if m, 

 ■if M, if M, and If M. These Mg(N03)2 solutions also killed 

 many embryos during the early stages of development. Cyclopia 

 occurred in from 4 per cent to 40 per cent of the eggs in |f M, 

 i| M, if M, if M, and if M. These strengths are comparable to 

 those most effective for MgCIs, both as to the amount of magnesium 

 present and as to osmotic pressure. 



Mixtures ofMgCU + NaCl; MgSO, + NaCl; and Mg {NO,), + 



NaCl 



Mixtures of MgClz and NaCl were added to sea-water as fol- 

 lows: 12 cc. of a molecular solution of MgClj was added to 12 cc. 

 of NaCl, and 36 cc. of sea-water was then taken to make the 

 entire quantity up to 60 cc. This solution will be spoken of as 

 i M + i M, the first term referring to the MgClj present and the 

 second to the NaCl. On this basis the following mixtures were 

 used : I M + i m, ^ m + i m, y\ m + i m, J^ m + i m, in which 

 the MgClj was varied and the NaCl kept constant, and ^ m + ^ 

 M, i M + 1 M, 2^0 M + ^ M, ^ M + J M, in which the amount of 

 NaCl was varied also. 



Such mixtures caused the development of cyclopia, the best 

 results were obtained in ^ m + i m, where as times as many as 

 25 per cent occurred. The ^V m + | m gave in one case 30 per 

 cent of cyclopia. The -g^ m + i m gave 1 1 per cent. It will be 

 seen that the amount of MgClj present in these mixtures is less 

 than that necessary to cause similar results when used alone. 

 This is a peculiar fact and one for which I know of no explana- 

 tion. Similar results (Stockard '07b) were found with mixtures 



