162 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
In this case the rise in the rate of oxidations is less than 
that ordinarily caused by membrane formation with butyric 
acid in the same eggs. 
TABLE XXXII 
UNFERTILIZED Eaas or S. purpuratus 
| Coefficient of 
Oxygen 
Consumption 
50 c.c. sea-water+ 4 ¢.c. 24 m NaCl+KCl+CaClL..... 1.4 
50 c.c. sea-water+ 6 c.c. 24 m NaCl+KCl+4+CaCL..... 1.9 
50 c.c. sea-water+ 8 e.c. 23 m NaCl+KCl+CaCl,..... 2.6 
50 ¢.c. seaewater+ 9 ¢.c. 24 m NaCl+KCl+CaClL..... 2.6 
50 ¢.c. sea-water+12 e.c. 24 m NaCl+KCl+CaCl..... We, S 
50 ¢.c. sea-water +16 c.c. 24 m NaC]l+KCli+CaClkL..... DAG 
2. The hypertonic solutions are much more effective in 
causing artificial parthenogenesis if some alkali is added. In 
one experiment 0, 0.5, 1.0, 1.5, and 2.0 c.c. N/10 NaOH were 
added each to 50 c.c. of sea-water+10 c.c. 25 m NaCl solution. 
The unfertilized eggs of one specimen of S. purpuratus were 
divided among these solutions and portions of the eggs trans- 
ferred to normal sea-water after 60, 90, 120, 150, and 240 
minutes. The temperature of the hypertonic sea-water was 
13.5°C. Only the two of these solutions with the highest 
concentration of NaOH (1.5 and 2.0 c.c. N/10 NaOH to 
50 c.c. of the hypertonic sea-water) caused the eggs to 
develop into larvae (time of exposure 13 hours). Some of 
these larvae reached the pluteus stage and swam at the sur- 
face of the dish. Often, however, the addition of quite a small 
amount of NaOH was enough to cause development and for 
the eggs of some females the concentration of HO ions pres- 
ent in the sea-water is sufficient. We are dealing here with 
differences in the eggs of various females. It was found in 
general that a neutral hypertonic solution was not able to induce 
artificial parthenogenesis in the eggs of S. purpuratus. Even 
the maximal permissible increase of the osmotic pressure is 
