ANTAGONISM BETWEEN SALTS AND ANESTHETICS 595 



sign of development or other change. If such eggs are fertihzed, 

 even after lying in sea-water for many hours (e.g., overnight) 

 they develop into free-swimming larvae, showing that the eggs 

 have not been essentially injured, but that the salt-solution has 

 simply been prevented by the anesthetic from exerting its usual 

 action. The degree of this preventive or antagonistic influence 

 was estimated by comparing the respective proportions of eggs 

 remaining thus unaltered after exposure to the pure and to the 

 anesthetic-containing salt-solutions. In the majority of experi- 

 ments eggs were also exposed — about fifteen minutes after the 

 treatment with salt-solution — to hypertonic sea-water (100 vol- 

 umes sea-water plus 16 volumes 2.5 in NaCl) for twenty min- 

 utes. The effect of the addition of anesthetics on the action of 

 the hypertonic sea-water was also investigated. In most of the 

 experiments the eggs were anesthetized in sea-water previously 

 to being exposed to the anesthetic-containing salt-solution, i.e., 

 were placed for about half an hour in sea-water containing the 

 same anesthetic in the same concentration as in the salt-solution. 

 The antagonistic influence of the anesthetic is found to be more 

 pronounced after this preliminary anesthetization than when 

 the eggs are transferred directly from normal sea-water to the 

 anesthetic-containing salt-solution. 



The details of the manipulation were kept as constant as 

 possible. Equal quantities of eggs from the same lot were used 

 in the different experiments of any series. The anesthetic-con- 

 taining solutions were prepared shortly before using and kept 

 in corked flasks. The brief exposure to the salt-solution was 

 made in finger-bowls; the pure or anesthetic-containing sea- water 

 was removed as far as possible and to the mass of eggs remain- 

 ing (usually 2 to 3 cc.) a relatively large volume (usually 50 cc.) 

 of the corresponding salt-solution was rapidly added; at the end 

 of the four or five minutes of exposure a large volume {ca. 300 cc.) 

 of sea-water was added and this was changed as soon as the eggs 

 had settled, and again one or more times later. The sea- water in 

 which the eggs were left after the final treatment was always 

 changed several times to remove the last traces of anesthetic. 



