PLATE 1 



EXPLANATION OF FIGURES 



Photomicrographs of inseminated Asterias eggs: 



1 and 2 Controls. Note that the spermatozoa are scattered. This shows 

 especially well in the right hand part of 1. 



3 Eggs from the same female treated for one hour with 0.3 per cent ether in 

 sea-water, washed, and then inseminated, with the same sperm suspension as 

 above. Note the spermatozoa in halos around both mature and immature eggs. 



500 



