278 ALVALYN E. WOODWARD. 



Since a solution of lipolysin in sea-water may be made much 

 more concentrated than the original secretion, it is not necessary 

 to expose the eggs so long to its action. In fact, one of the 

 most sensational results was the development to the trochophore 

 stage of 50 per cent, of the eggs exposed for one minute to a 

 solution of Echinarachnius lipolysin. Most of those eggs con- 

 tinued to develop, and formed segmented worms. The solution 

 used, so-called I per cent., was made by dissolving .1 c.c. pow- 

 dered lipolysin in 10 c.c filtered sea- water. 



In a third series of experiments, dilute Arbacia egg-secretion 

 was passed through a Berkfeldt filter. In this process, the 

 agglutinin remains on the filter and the lipolysin, with other 

 substances, passes through. Nereis eggs which were left in this 

 filtrate eighteen hours underwent maturation and divided 

 regularly into eight or more cells. They were then transferred 

 to sea-water, in which they continued to develop into normal 

 larvae. 1 



It was suggested by Dr. F. R. Lillie that the effect of egg- 

 secretion was simply that of a foreign protein, and might be 

 imitated by using ccelomic fluid. Following this suggestion, I 

 subjected Nereis eggs to the ccelomic fluid from Asterias, treating 

 them w r ith various dilutions and for varying periods of time. 

 While some eggs formed polar bodies and secreted jelly, only a 

 few started to divide, and that very irregularly. I did not 

 succeed in finding any method by means of which the serum 

 would produce normal division or swimming larva?. 



These experiments with Nereis eggs continue a series begun 

 several years ago by O. C. Glaser ('14) who found that Asterias 

 eggs could be stimulated to divide by letting them stand in 

 Arbacia egg-secretion. The following year I performed the 

 reciprocal experiment, which helped to show that the partheno- 

 genetic agent in egg-secretion is not specific. Later, I found 

 that Asterias lipolysin produced as many larvae in Arbacia eggs 

 as did Arbacia lipolysin (Woodward, '18). The present work 

 shows that the parthenogenetic agent in echinoderm egg-secre- 

 tions is not even limited in its efficacy to eggs of the same phylum, 



1 This experiment was first performed by Miss M. M. Sampson and repeated 

 by myself. 



