STUDIES IN ARTIFICIAL PARTHENOGENESIS. 



results obtained with the centrifuging method are still more 

 convincing. 



At 10:02^ A.M. (July 23, 1914), 2.5 c.c. of toluol were added 

 to 2.5 c.c. of sea- water containing eggs, and the mixture was 

 stirred thoroughly with a glass rod (in a Syracuse watch-crystal). 

 At 10:07^ A.M., 7 drops of the egg-containing liquid were 

 transferred back to normal sea-water. Into one tube of the 

 centrifuge were placed normal eggs, the other contained eggs 

 which had been treated with toluol for five minutes. The eggs 

 were then centrifuged for 30 seconds at a rate of 152 revolutions 

 per second. Upon examination, the normal eggs appeared 

 perfectly stratified, whereas those which had been exposed to 

 toluol showed not a trace of stratification. As a result of the 

 toluol treatment the eggs increased their diameter about 2/4. 

 The experiment was repeated with identical results on July 25, 

 I c.c. of toluol being added to 3 c.c. of sea-water. In this case 

 the eggs were exposed 5 minutes, and were then centrifuged 

 23 seconds at an average of 158 revolutions per second. 



Saponin was also found to produce a coagulation within the 

 egg. At 5:35 P.M. (July 23), 7 drops of an egg suspension 

 were placed in about 15 c.c. of 0.2 per cent, saponin solution 

 (in sea-water). -At 5 140 P.M., the eggs were returned to normal 

 sea- water. The eggs were then subjected to an exceptionally 

 long centrifuging process. Beginning at 5:47 P.M., for 50 

 seconds they were revolved at an average of 166.5 revolutions 

 per second. Normal eggs subjected to this centrifuging process 

 were of course completely stratified. Of the eggs treated with 

 saponin, only about 15-20 per cent, showed any signs of strati- 

 fication, the remaining eggs were all totally unstratified. 



In the experiments with saponin and toluol, the reagent pro- 

 duces a lowering of surface tension directly. With some re- 

 agents, membrane swelling occurs first, and the lowered surface 

 tension thus produced results in endosmosis. In this case also, 

 coagulation follows an increase in egg volume. On August 4, 

 1914, eggs were washed in 0.55 M NaCl solution and were then 

 dropped into 0.55 M NaCl plus 1.5 c.c. N/io NaOH at 10:59^ 

 A.M. These eggs were then placed into one tube of the centri- 

 fuge, and into the other were placed eggs which had been im- 



