JACQUES LOEB 



8 



10 n 12 13 



Figs. 1 to G Five days old plutei of Strongylocentrotus purpuratus produced 

 by artificial parthenogenesis. 



Figs. 7 to 9. Five days old plutei of Strongylocentrotus purpuratus 9 and 

 Strongylocentrotus franciscanus cT. 



Fig. 10 to 13 Five days old plutei from Strongylocentrotus puipuratus 9 and 

 Asterias cf. 



