FERTILIZATION ON PARTHENOGENESIS. 



Supernatant fluid of B, E, and F eggs of the experiment was 

 quite decidedly colored by escaping pigment from broken down 

 or injured eggs. In the B lot fertilization was much more nearly 

 that of the normal process than was D, E, F, or G approximately 

 70 per cent, of swimming larvae were noted in B, while only a 

 very small per cent. (10 per cent, to 15 per cent.) were found in 

 the lots that were given a longer butyric treatment; yet we see 

 little difference in the intensity of the agglutination reaction. 

 The tests are complicated by the entrance of the secondary sub- 

 stances diffusing from the eggs. A study of these conditions 

 may reveal striking results. The writer has been entirely unable 

 to produce a curve of fertilizin production that will run parallel 

 to that of fertilization. One fact, however, is to be noted with 

 emphasis. In no case has he ever obtained fertilization of the 

 eggs of Arbacia when the fertilizin reaction was negative. 

 Whether this will always hold true remains for further investi- 

 gation to prove. 



3. Conditions where Fertilization is Absent. 



Since the hypothesis of fertilizin production holds good for 

 all cases of fertilization in the curve where cleavage follows 

 fertilization, the writer was anxious to know if it served equally 

 well as a possible indication of the internal conditions of eggs 

 that would not fertilize. We have seen in these experiments 

 three instances of treatment that prohibit fertilization; penetra- 

 tion of sperm was not prohibited for we have seen in each of the 

 cases of (i) an optimum exposure to butyric acid and subsequent 

 destruction of membranes; (2) prolonged exposure to butyric 

 acid (10 minutes); and (3) exposure to temperature of 35 C. 

 for 10 minutes, that sperm entered in considerable numbers. 



Does fertilization then depend upon the presence of fertilizin? 



The results of observations on all three conditions answer 

 this in the affirmative. When eggs are given the optimum 

 butyric acid treatment and full membranes are produced fer- 

 tilizin is not detectable in the supernatant fluid of such eggs after 

 a few washings. 



pensions made from dry sperm that has not been standing too long, especially if 

 the original quantity is small. Suspensions should not be older than five minutes 

 or ten minutes at most, if delicate results are desired. 



