EFFECT OF X-RADIATION ON FERTILIZIN. 



145 



wore off when the fertihzin had stood for some time. If this is 

 true in general it must follow that, since the fertilizin must stand 

 in the parthenogenesis experiments, there would be irregularity 

 in the results. 



The only tests of the effect of x- radiation on Asterias fertilizin 

 were made on July 28, when the fertilizin was divided into four 

 portions, as usual. One was kept for a control, one radiated two 

 minutes, one five minutes, and the fourth fifteen minutes. The 

 fertilizin was then put on mature Asterias eggs, which were 

 allowed to stand two hours in the solution. They were then 

 rinsed with sea-water and treated with hypertonic sea-water 

 (50 c.c. sea water -f- 8 c.c. 2.5 M. NaCl) for thirty minutes, 

 washed again with sea water, and allowed to stand for 12 hours. 

 All four lots of eggs showed parthenogenetic development, and 

 those treated with fertilizin which had been radiated 2 minutes 

 had a much larger percentage of cleavages than either the 

 control or the others. 



Several times Arbacia fertilizin was similarly subjected to 

 x-rays and then tested for its auto-parthenogenetic effect on 

 fresh Arbacia eggs. The experiments are not satisfactory, 

 because in most cases eggs from the same females gave abnormal 

 results when tested in other ways. The following summarizes 

 the more interesting experiments. Percentages were obtained 

 by counting about 200 eggs. 



Table II. 



Since the effect of x- radiation on fertilizin seems to be similar 

 to its effect on enzymes, it is of interest to note the fact that the 



