STUDIES IN ARTIFICIAL PARTHENOGENESIS. 157 



The above egg showed a completely unswollen membrane, and so should be ex- 

 cluded from the experiment. 



63.5 65 at about 11.20 A.M. 



67 67.5 at ii. 24 A.M. 



Average 66.2 /j. (egg with unswollen membrane excluded). 



The eggs used in the above experiment were all from a single 

 female. The normal untreated eggs of this female were practi- 

 cally spherical and measured 74. 5M, 75M, 75/*i 74M, 75M, 75M, 75/". 

 75Mi 75-5M> 75M- They thus possessed an average diameter of 

 75/x and were practically all of the same size. The experiment 

 shows that the eggs in B with swollen membranes shrank more 

 than did the eggs in A with unswollen membranes. 1 The average 

 decrease in diameter of the former was about 9^1, of the latter 

 about 6^. The difference was also constant, for the largest egg 

 with swollen membrane was smaller than the smallest egg with 

 unswollen membrane. 



August 23. Two small stender dishes were used. A con- 

 tained 29 c.c. of "NaCl hypertonic sea-water," which had been 

 made up on August 18 (at n 130 'P.M.). B contained 25 c.c. 

 of sea-water. At 9.55 A.M., 4 drops of an egg suspension were 

 dropped into A and the same amount in B, and then 4 c.c. 

 2.5 TV NaCl were added to B, so that this solution became 

 "NaCl hypertonic sea-water." The diameter of the eggs was 

 determined as in the previous experiment. At 10:25 it was 

 noticed that some of the eggs in A were beginning to acquire 

 swollen membranes, so that only a few measurements were 

 made after this time, and only those eggs with unswollen mem- 

 branes were selected. 



DIAMETER OF EGGS IN A. 



65 fj. X 65 /j. at 10.12 A.M. 



65 66 at 10.13 A.M. 



67.5 70 at 10.14 A.M. 



65 70 at 10.15 A.M. 



65 68 at 10. 16 A.M. 



63.5 X 70.5 at 10.17 A.M. 



65 66 at 10.18 A.M. 



1 This result was obtained in spite of the fact that membrane swelling always 

 tends to produce an increase in egg volume. Whenever membrane swelling occurs 

 in isotonic solutions, the egg rapidly increases its volume, it cytolyzes. The cause 

 of this cytolysis resulting from membrane swelling will be considered later. 



