ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 963 
however, acting as completely as it does in the sea-urchin egg 
after membrane formation. 
4. Mead! observed that the addition of a small amount of 
KCl to the sea-water causes the eggs of Chaetopterus to throw 
out their polar bodies, and the writer observed that the same 
procedure causes these eggs to develop into larvae I had 
already expressed the suspicion that these eggs develop into 
larvae without segmentation. F. Lillie made sure of this fact 
by a cytological examination of the eggs.° 
All efforts to cause this egg to undergo development with 
normal segmentation failed until Wasteneys and the writer 
tried the effects of foreign blood serum. The eggs were put for 
from 14 to 23 minutes into a mixture of 25 .c. 3/8m SrCl,+ 
25.c.c. m/Z (NaCl+KCl+CaCl,), then for 10 minutes into 
ox serum diluted with its own volume of m/2 Ringer solution 
and then for 30 minutes into hypertonic sea-water. Such eggs 
when transferred back to normal sea-water segmented and de- 
veloped into larvae.* They were usually not normal larvae, 
inasmuch as they showed a tendency to stick to the glass and 
to each other. Moreover, the cleavage cells of the same egg 
fell apart easily. The method needs further improvement. 
5. Lefevre succeeded in causing artificial parthenogenesis 
in the eggs of Thalassema mellita, a marine annelid of North 
Carolina.2 The eggs of this worm are fertilized in the oocyte 
stage, just like those of Polynoe. The entry of the spermato- 
zoon leads to the formation of a fertilization membrane; the 
two polar bodies are then extruded, and segmentation and devel- 
opment start after maturation is complete. Now Lefevre 
found that when the unripe eggs of Thalassema are exposed to 
1 Mead, Biological Lectures delivered at Woods Hole, 1898. 
2Loeb, Am. Jour. Physiol., IV, 423, 1901. 
3. R. Lillie, Archiv f. Entwicklungsmechanik, XIV, 477, 1902. 
4 Loeb and Wasteneys, Science, XX XVI, 255, 1912. 
5 G. Lefevre, ‘‘ Artificial Parthenogenesis in Thalassema mellita,’’ Jour. Exper. 
Zool., IV, 91, 1907. 
