The Influence of External Factors on Development 1 99 



the embryos in the weaker solutions hatched but swam abnormally. 

 Solutions of MnClj in sea-water induced similar effects. 



J Sea-water solutions of MgClj caused the embryos to form 

 one large single and almost terminal eye. This single eye results 

 from an early fusion of the two optic vesicles. The optic cup is, 

 therefore, abnormally large and the size of the lens in such eyes 

 varies directly with the size of the optic cup. This condition is to 

 be compared with that known in human monsters as Cyclopia. 

 MgCis when mixed with NaCl also caused this abnormality. 



e Eggs that were treated with NaCl solutions showed no 

 abnormalities during their early development. In the weaker 

 solutions many embryos hatched but were unable to swim in a 

 normal fashion. The NaCl affects either the nerve or muscle 

 substance of these fish causing them to swim with jerky motions, 

 and to fall on one side when at rest. The embryos would live 

 for many weeks without hatching in very strong NaCl solutions. 



6 Mixed solutions of salts and sugar act more violently on 

 these eggs than either constituent would if used alone. Very 

 small doses of a salt will give the effect of a much stronger dose, 

 provided that sugar has been added to the solution. The presence 

 of the sugar thus seems to augment the activity of the salt. This 

 may be due to the additional osmotic pressure that the sugar 

 exerts, but such an explanation is not entirely satisfactory. 



Pathological Laboratory 

 Cornell University Medical College 

 New York City, December i, 1906 



LITERATURE CITED 



Brown, O. H., '03 — The Immunity of Fundulus Eggs and Embryos to Electrical 



Stimulation. Am. Jour. Physiol., ix, pp. 111-115. 

 '05. The Permeability of the Membrane of the Egg of Fundulus Hetero- 



clitus. Am. Journ. Physiol., xiv, pp. 354-358. 

 Garrey, W. E., '05 — ^The Osmotic Pressure of Sea-water and of the Blood of 



Marine Animals. Biol. Bull., viii, pp. 257-270. 

 GuRWiTSCH, A., '95 — Ueber die Einwirkung des Lithionchlorids auf die Entwick- 



elung des Frosch und Kroteneier (Rana fusca und Bufo vulg.). 



Anat. Anz., xi, pp. 65-70. 



