160 Artificial Parthenogenesis and Fertilization 



membrane formation by butyric acid is much more reliable 

 than that by the hypertonic solution. 



The membrane-forming action of a hypertonic solution is 

 similar to that of a base, and this can be demonstrated in the 

 liquefaction of the chorion of the egg of Lottia (a mollusc). 

 We have mentioned that this chorion can be caused to swell 

 and undergo liquefaction by bases. The writer found that the 

 same can be accompUshed by neutral hypertonic solutions.' In 

 both cases the presence of free oxygen is required. Moreover, 

 the temperature coefficient for the dissolution of the chorion in 

 the unfertilized egg of Lottia by hypertonic solutions is over 

 2 for 10° C. 



The idea that in the causation of artificial parthenogenesis 

 by the original purely osmotic method the latter acted in the 

 double capacity of a membrane-forming and corrective agency 

 can be supported by measurements of the rate of oxidation of 

 unfertilized eggs in these solutions. 



According to our theory the rise in the rate of oxidations in 

 unfertilized eggs under the influence of hypertonic solutions 

 should be due only to the alteration of the surface of the 

 egg, i.e., the membrane formation. Since this effect takes 

 place, if it takes place at all, in the first two hours, we should 

 expect .that if we leave unfertilized eggs for a series of hours 

 in a hypertonic solution, and measure the rate of oxida- 

 tion for successive hours, the maximum effect should be reached 

 in the first or second hour and that afterward the hypertonic 

 solution should cause no further rise in the rate of oxidations. 

 This actually takes place. The following experiment gives the 

 rate of oxidations of unfertihzed eggs in a hypertonic solution 

 in a series of successive hours.^ The consumption of oxygen 

 was measured for one hour at 18°. Unfertilized eggs were 



■ Loeb, " On a Chemical Method by Which the Eggs of Lottia Can Be Caused 

 to Become Mature," C/fttperst^y 0/ California Publications, VhysioXij^y, 111, 1, 1905. 

 ' Loeb and Wasteneys, Jour. Biol. Chem., XIV, -169, 1913. 



