OSMO-REGUIATION 



239 



distilled water 



tap water 



stindard solutLOn 



frog Ringer 



The relative size of unfertilized eggs of 

 R. pipiens, expressed as percentage 

 increase or decrease from the initial 

 size (indicated by 100), after exposure 

 to salt solutions of varying osmotic 

 pressure. 21 to 24 C. 



Effects of various osmotic 

 pressure upon amphibian 

 cells up to the neurula 

 stage. pH 7.6 to 8.2. 



Neuniloe of Triturus torosus exposed 

 (a) to Ringer, (b) to standard 

 solution, (c) to tap water display 

 varying degrees of retarded develop- 

 ment and lose mesoctoderm cells. 



From Holtfreter, 1943. Jour. Exp. Zool. 93:251. 



