110 JACQUES LOEB. 



eggs of some females will develop into larvae, while the eggs of 

 others will not. The writer assumed that the hypertonic solution 

 if applied to the unfertilized egg has two effects, one consisting 

 in the alteration of the surface layer (comparable to the effect 

 of butyric acid) and secondly the corrective effect. Wasteneys 

 and the writer 1 published a series of measurements on the in- 

 fluence of a hypertonic solution on the rate of oxidations in 

 unfertilized eggs of purpuratus, and found that the effect varied 

 enormously with the eggs of various females. The eggs were 

 in the hypertonic solution for one hour and the rate of increase 

 in oxidation varied for the eggs of various females between 40 

 and 400 per cent. As we stated above, the eggs of only a limited 

 number of purpuratus can be induced to develop into larvae 

 by a mere treatment with a hypertonic solution and it is probable 

 that the eggs in which the oxidations were raised efficiently were 

 the ones that could be induced to develop into larvae in this way, 

 while those in which the rate of oxidations was not raised to the 

 same height did not segment. We also noticed that in the latter 

 type of eggs the rate of oxidations diminishes after some time. 

 It is possible that the reversion of development in such cases is 

 due to a decline in the rate of oxidations below the height re- 

 quired for development. 



The same possibility holds for the lack of development of the 

 eggs after artificial membrane formation through butyric acid 

 when they are afterwards put into a solution of NaCl + KC1 

 + CaCl 2 (instead of into sea- water). The fact that no correct 

 membrane is formed and that the eggs neither develop nor dis- 

 integrate, and behave towards a treatment with the hypertonic 

 solution like eggs without a membrane, arouses the suspicion 

 that in this case the butyric acid treatment did not lead to the 

 proper increase in the rate of oxidations. It is intended to in- 

 vestigate this possibility next summer, since it may also furnish 

 the explanation of the phenomena of reversibility in development. 



1 Loeb and Wasteneys, Jour. Biol. Chem., XIV., 474, 1913. 



