AUTO-PARTHENOGENESIS IN ARBACIA AND ASTERIAS. 397 



Since the fertilizin theory postulates essentially the same 

 machinery for auto-parthenogenesis and normal fertilization it 

 follows that initiation by living sperm should also be blocked 

 by treating the eggs with the boiled sperm-infusion. This is 

 actually the case: 



Eggs treated for two hours with strong boiled sperm-infusion. 

 At the end of this period they were heavily inseminated with 

 living sperm, but remained unfertilized. Only a few cleav- 

 ages were observed later, but these were arrested at the latest 

 in the four-cell stage. No further development occurred, 

 but on the following day practically all the eggs exhibited 

 fertilization membranes. Controls normal. 



3. The Prevention of Auto-parthenogenesis by Means of a Group 

 Split from the Secretion. F. R. Lillie ('i3 2 ) finds the agglutinative 

 power of egg-secretion unimpaired, or perhaps better, not meas- 

 urably impaired, by boiling for 5 minutes, although the solution 

 undergoes a change of color due to the formation of small quan- 

 tities of a purple compound ('i4 2 ). As the secretion is thus visibly 

 different in chemical composition it becomes important to ascer- 

 tain whether the formation or presence of the purple compound 

 makes any recognizable difference in the initiation of development. 

 The following experiments indicate that the efficacy of the secre- 

 tion as a parthenogenetic agent is blocked. 



Standard secretion boiled. Purple compound formed. Sperm- 

 agglutination positive. 



3.20 P.M. I volume of boiled secretion added to I volume of 

 fresh egg-suspension. 



8.00 P.M. No cleavages. 



8.00 A.M. Few delayed cleavages, not at all in normal 

 frequency. 



11.30 A.M. i volume of boiled secretion added to I volume 

 of fresh egg-suspension. 



2.00 P. M. No cleavages. 



7.00 P.M. No cleavages. 



8.30 A.M. No cleavages. 



Control in unboiled secretion exhibited auto-parthenogenesis, 

 in usual quantity. 



