ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 649 
once started an experiment, although I knew that it was 
practically impossible to exclude contamination by sperma- 
tozoa if I attempted to isolate the eggs immediately after 
having handled a male. The female was washed off in steril- 
ized sea-water, but of course I was aware that this would 
not suffice to get rid of any spermatozoa that might be stick- 
ing to the surface of the animal. The eggs, however, were 
taken and distributed into the following five solutions: 
(1) 6c. 24n KCl+94 c.c. sea-water 
Q) 8 “ +92 “ 
(3) 10 “ +90 “ 
(4) 12 “ +88 “ 
(5) Normal sea-water (control) 
One part of the eggs remained one hour and twenty-five 
minutes, the rest one hour and forty minutes in the solu- 
tions. The experiment was started in the afternoon. The 
next morning’ I found numerous swimming larve (trocho- 
phores) in the material that had been in the first four solu- 
tions for one hour and twenty-five minutes. In the second 
lot they were less numerous. But even in the control 
material I found two swimming trochophores. It followed 
that the Chetopterus were either naturally parthenogenetic or 
the precautions against the entrance of spermatozoa had not 
been sufficient. 
Second series.—From now on I applied the rigid anti- 
septic measures against spermatozoa described above in the 
introduction. The following solutions were used: 
(1) 8ec.24n KCl +92 c.c. sea-water 
(2) 10cc.24n KCl +90 «“ 
(3) 12c.c.2kn KCl +88 «“ 
(4) 12e.e. 2in NaCl +88 “ 
(5) 20 cc. 24n MgCl, +80 © 
(6) Normal sea-water (control) 
1] shall in the following descriptiou of the experiments consider only whether 
or not swimming trochophores were formed. The morphological details will be 
given insection v. It goes without saying that all the experiments deal with unfertil- 
ized eggs, unless the contrary is distinctly stated. 
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