ArtificiaUy Produced Cyclopean Fish 289 



» 

 At the maximum point the normal or ordinary individuals, which 

 predominate, would be affected, and here the greatest number of 

 Cyclopean embryos occur. 



As I previously mentioned, the MgCla is found to be rather 

 toxic to these eggs during the earlier stages of development. Many 

 die at this time, but in the medium strength solutions 70 to 80 

 per cent live and form embryos and in the weaker solutions often 

 more than 90 per cent live. After the early embryo is formed, 

 however, the high death rate falls and a dead embryo is of rare 

 occurrence in any of the solutions. Many embryos were kept 

 in the solutions thirty days and some hatched in strengths as strong 

 as if M. If, on the other hand, the eggs are removed from the 

 solutions when sixty or seventy hours old, when the cyclopean 

 condition is readily distinguishable, and placed in sea-water 

 they grow much better and many hatch normally. Some of the 

 cyclopean fish came out on the twelfth day after fertilization, 

 though usually they were much slower in emerging. The control 

 embryos hatch in from eleven to twenty days, depending chiefly 

 upon the temperature. 



Solutions of MgCl^ in Distilled Water 



Distilled water solutions of MgClj of several strengths; i^ M, 

 xr. M, if M, if M, ii M and i^ M were not effective. The eggs 

 either died during early stages or developed into embryos with 

 two normal eyes. I had found (1906) that salts of lithium induce 

 the same typical defects in Fundulus eggs in both sea-water and 

 distilled water solutions. Such solutions have opposite conditions 

 of pressure, being in one case hypertonic and in the other hypo- 

 tonic and thus remove all question of osmotic effects as a cause. 

 It was hoped that Mg might also act in the two solutions which 

 would have made it certain that the direct action of the magnesium 

 ion is responsible for the cyclopean condition of these embryos. 

 The problem of cyclopean formation seems, however, to be more 

 complex. It involves the action of magnesium in the presence 

 of certain or all of the sea-water salts. 



