190 Charles R. Stockard 



more embryos had hatched than in the control though all of these 

 fish swim with a jerky motion often movmg in a spiral course or 

 even turning somersaults in the water. The salt seems to act 

 either upon the nerves or muscle fibers of the embryo causing the 

 nervous twitching or jumping movements. The pectoral fins 

 seem to lack their usual coordination. This condition is not 

 induced by the absence of some constituent of the sea-water since 

 embryos hatched in distilled water swim normally. The result is 

 then undoubtedly due to the action of the NaCl. The embryos 

 die within one or two days after hatching with their bodies pecul- 

 iarly curled or twisted. Jenkinson ( '06) has lately recorded a simi- 

 lar twisting and inability to swim for newly hatched tadpoles in 

 NaCl solutions. 



Sea-water solutions of f m, f m and molecular concentrations of 

 NaCl showed only a tendency to shrink the yolk. The develop- 

 ment progressed almost normally and only a few eggs died. On 

 their shrunken yolks the embryos when six days old were small and 

 behind the control in their development. At fourteen days the 

 embryos hatched in the | m and f m solutions, those in the weaker 

 solution swam normally while those in the stronger showed the 

 same jerky motions described above. On comparing these effects 

 with those in the distilled water solutions it is reasonable to suppose 

 that some constituent of the sea-water is capable of counteracting 

 the effect of NaCl up to a given point" but when an excessive 

 amount of the salt is present its action is not entirely checked. 



Eggs lived for twenty-four days in a healthy condition in the 

 molecular NaCl solution although none of them hatched. Loeb 

 kept eggs as long as five weeks in a NaCl solution in sea-water 

 without hatching. 



Embryos three days old were subjected to a double molecular 



' In 1902 Loeb found that Fuudiilus embryos ■^ould not develop in a solution of NaCl in distilled 

 water equivalent to the concentration of NaCl in the sea; he then added a trace of calcium salt and 

 found development to be normal. After a number of experiments the conclusion was reached that the 

 salts of monovalent cations with monovalent anions esert a tosic effect at certain concentrations. 

 This toxic effect could be apuihilated through the addition of a small amount of a salt having a 

 bivalent cation or by a still smaller amount of one having a trivalent cation. In other words, the 

 antitoxic effects of cations vary directly as the valence of the elements. It was also found that 

 mono-, bi-, or trivalent anions were all unable to produce a like effect. 



