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 accomplished by neutrai 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 l0=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 unfertilized 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 
1 Loeb, ‘‘On a Chemical Method by Which the Eggs of Lottia Can Be Caused 
to Become Mature,’ University of California Publications, Physiology, III, 1, 1905. 
2 Loeb and Wasteneys, Jour. Biol. Chem., XIV, 469, 1913. 
