192 Charles R. Stockard 



with frog's eggs and concludes that in order to be effective the two 

 solutions together must exert a higher pressure than the one pro- 

 ducing its effect at the lower limit but less than for the other that 

 produces its effect at a higher pressure. These osmotic pressure 

 effects are somewhat contr: dictory as I have above pointed out in 

 mentioning Morgan's results in which he finds the upper limit of 

 NaCl to be about 2 per cent with a pressure of 13.61 atmospheres, 

 while a like fatal limit for sugar was found to exert a pressure of 

 only 8.376 atmospheres. It is also recalled that I described above 

 a like contradiction in comparing the pressures of fatal sea-water 

 solutions of sugar with similar solutions of MgCl,. As there 

 stated, this contradiction is possibly due to the fact that the cane 

 sugar in solution becomes inverted and thus the actual pressure is 

 really double that calculated. 



In working with Fundulus eggs, as has been already pointed out, 

 the experimenter has the advantage of being able to keep them 

 alive in solutions which exert pressures both above and below that 

 to which the eggs are normally accustomed. This fact has been of 

 especial value in analyzing the results of the following experiments. 

 To anticipate what is to follow it may be stated that on adding 

 certain percentages of sugar to a distilled water salt-solution, the 

 action of the salt was increased although the total pressure of the 

 solution was less than the osmotic pressure of ordinary sea-water. 

 Such a result may probably be due to the action which would take 

 place if the sugar became inverted in the solution. 



The following distilled water solutions of LiCl + sugar were 

 employed in one experiment, LiCl 0.128 m, 0.096 m, 0.064 'ti 

 and 0.032 m with 0.44 m of cane sugar in each. All of these solu- 

 tions exert an osmotic pressure less than that of sea-water, except 

 possibly the first which has an almost equal pressure. After nine- 

 teen hours the eggs in LiCl 0.128 m + 0.44 m sugar had polar 

 caps with "bubbles" beneath and many were dead, those in LiCl 

 0.096 m + 0.44 m sugar were in about the same condition. LiCl 

 0.064 "^ + 0-44 m sugar had also produced polar caps and no germ- 

 rings were formed, LiCl 0.032 m + 0.44 m sugar had caused half 

 of the embryos in it to die, while the living ones had formed abnor- 

 mal germ-rings. Eggs in a solution of LiCl 0.032 m are scarcely 



