Artificially Produced Cyclopean Fish 333 



The part in anaesthesia lacks energy to grow out laterally, thus the 

 two eye anlagen remain together in the floor of the brain and come 

 off as one median vesicle either double or single, depending upon 

 the extent of separation possible under the given degree of pres- 

 sure or anaesthesia. 



Mall ('08), in his recent memoir on the causes underlying the 

 origin of human monsters, gives an excellent survey and discussion 

 of the evidence furnished by experimental teratology. In the 

 body of the paper is presented a strong case in favor of external 

 influence during development as the chief cause of many mon- 

 strosities. Here we may consider only the discussion of cyclopia. 

 The idea of fusion of the two eye vesicles during their develop- 

 ment is advocated, but the present evidence is against this posi- 

 tion and is in accord with Spemann's ('04) view of an early defec- 

 tive anlage. Mall also inclines toward the idea of the single 

 brain as being primarily responsible for cyclopia, but it is shown 

 by embryos considered here that cyclopia often accompanies 

 perfectly bilateral and bilobed brains, neither does a retarded 

 growth of the frontal process necessarily follow in cases of cyclopia. 



Experiments uphold the statement "that every egg has in it the 

 power to develop cyclops monsters." The germinal theories of 

 cyclopia are shown by the experiments to be unnecessary as ex- 

 planations of its cause. The possibility of its occurrence through 

 germinal variations, though to my mind extremely slight, is not 

 entirely excluded by experiments. The experiments conclusively 

 show the origin of cyclopia through external influences. 



Much could be said pro and con regarding the significant nature 

 of the Cyclopean fish embryos as a specific response to a definite 

 chemical environment. The suggestion is evident, though highly 

 hypothetical, that cyclopia in man and mammals might be due 

 to a similar chemical cause, an excess of Mg salts in either the 

 mother's blood or the amniotic fluid surrounding the developing 

 embryo. 



The Magnesium embryo is as typical of these Mg solutions as is 

 the now classic lithium larva of the sea urchin produced by Herbst 

 ('92, '93) in his Li solutions, or Morgan's ('04) lithium frog em- 

 bryos produced in a similar way. They all tend to show that dif- 



